fix potential Spectre variant 1 issues

In reply to Mauro Carvalho Chehab

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
 drivers/media/usb/tm6000/tm6000-video.c | 2 ++
 1 file changed, 2 insertions(+)

drivers/media/usb/tm6000/tm6000-video.c +2 -0

index b2399d4..d701027 100644
@@ -26,6 +26,7 @@
 #include <linux/kthread.h>
 #include <linux/highmem.h>
 #include <linux/freezer.h>
+#include <linux/nospec.h>
 
 #include "tm6000-regs.h"
 #include "tm6000.h"

@@ -875,6 +876,7 @@ static int vidioc_enum_fmt_vid_cap(struct file *file, void  *priv,
 	if (f->index >= ARRAY_SIZE(format))
 		return -EINVAL;
 
+	f->index = array_index_nospec(f->index, ARRAY_SIZE(format));
 	strlcpy(f->description, format[f->index].name, sizeof(f->description));
 	f->pixelformat = format[f->index].fourcc;
 	return 0;

Signature · 1 line

2.7.4

Mauro Carvalho Chehab

maintainer

2018-04-23 18:25 UTC #2 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Em Mon, 23 Apr 2018 12:38:03 -0500
"Gustavo A. R. Silva" <[email protected]> escreveu:

Quoted 35 lines

f->index can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.
Smatch warning:
drivers/media/usb/tm6000/tm6000-video.c:879 vidioc_enum_fmt_vid_cap() warn: potential spectre issue 'format'
Fix this by sanitizing f->index before using it to index array _format_
Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1].
[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
Cc [email protected]
Reported-by Dan Carpenter <[email protected]>
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
 drivers/media/usb/tm6000/tm6000-video.c | 2 ++
 1 file changed, 2 insertions(+)
drivers/media/usb/tm6000/tm6000-video.c +1 -0
index b2399d4..d701027 100644
@@ -26,6 +26,7 @@
 #include <linux/kthread.h>
 #include <linux/highmem.h>
 #include <linux/freezer.h>
+#include <linux/nospec.h>
 
 #include "tm6000-regs.h"
 #include "tm6000.h"

drivers/media/usb/tm6000/tm6000-video.c static int vidioc_enum_fmt_vid_cap(struct file *file, void *priv, · line 879

Quoted 4 lines

drivers/media/usb/tm6000/tm6000-video.c +1 -0

@@ -875,6 +876,7 @@ static int vidioc_enum_fmt_vid_cap(struct file *file, void  *priv,
 	if (f->index >= ARRAY_SIZE(format))
 		return -EINVAL;
 
+	f->index = array_index_nospec(f->index, ARRAY_SIZE(format));

Please enlighten me: how do you think this could be exploited?

When an application calls VIDIOC_ENUM_FMT from a /dev/video0 device, it will just enumerate a hardware functionality, with is constant for a given hardware piece.

The way it works is that userspace do something like:

	int ret = 0;

	for (i = 0; ret == 0; i++) {
		ret = ioctl(VIDIOC_ENUM_FMT, ...);
	}

in order to read an entire const table.

Usually, it doesn't require any special privilege to call this ioctl, but, even if someone changes its permission to 0x400, a simple lsusb output is enough to know what hardware model is there. A lsmod or cat /proc/modules) also tells that the tm6000 module was loaded, with is a very good hint that the tm6000 is there or was there in the past.

In the specific case of tm6000, all hardware supports exactly the same formats, as this is usually defined per-driver. So, a quick look at the driver is enough to know exactly what the ioctl would answer. Also, the net is full of other resources that would allow anyone to get the supported formats for a piece of hardware.

Even assuming that the OS doesn't have lsusb, that /proc is not mounted, that /dev/video0 require special permissions, that the potential attacker doesn't have physical access to the equipment (in order to see if an USB board is plugged), etc... What possible harm he could do by identifying a hardware feature?

Similar notes for the other patches to drivers/media in this
series: let's not just start adding bloatware where not needed.

Please notice that I'm fine if you want to submit potential Spectre variant 1 fixups, but if you're willing to do so, please provide an explanation about the potential threat scenarios that you're identifying at the code.

Dan,

It probably makes sense to have somewhere at smatch a place where we could explicitly mark the false-positives, in order to avoid use to receive patches that would just add an extra delay where it is not needed.

Regards,
Mauro

Gustavo A. R. Silva

author

2018-04-23 19:11 UTC #3 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Quoted 86 lines · Mauro Carvalho Chehab

Em Mon, 23 Apr 2018 12:38:03 -0500
"Gustavo A. R. Silva" <[email protected]> escreveu:
Quoted 35 lines
f->index can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.
Smatch warning:
drivers/media/usb/tm6000/tm6000-video.c:879 vidioc_enum_fmt_vid_cap() warn: potential spectre issue 'format'
Fix this by sanitizing f->index before using it to index array _format_
Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1].
[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
Cc [email protected]
Reported-by Dan Carpenter <[email protected]>
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
  drivers/media/usb/tm6000/tm6000-video.c | 2 ++
  1 file changed, 2 insertions(+)
drivers/media/usb/tm6000/tm6000-video.c +1 -0
index b2399d4..d701027 100644
@@ -26,6 +26,7 @@
  #include <linux/kthread.h>
  #include <linux/highmem.h>
  #include <linux/freezer.h>
+#include <linux/nospec.h>
 
  #include "tm6000-regs.h"
  #include "tm6000.h"
drivers/media/usb/tm6000/tm6000-video.c static int vidioc_enum_fmt_vid_cap(struct file *file, void *priv, · line 879
Quoted 4 lines
drivers/media/usb/tm6000/tm6000-video.c +1 -0
@@ -875,6 +876,7 @@ static int vidioc_enum_fmt_vid_cap(struct file *file, void  *priv,
  	if (f->index >= ARRAY_SIZE(format))
  		return -EINVAL;
 
+	f->index = array_index_nospec(f->index, ARRAY_SIZE(format));
Please enlighten me: how do you think this could be exploited?
When an application calls VIDIOC_ENUM_FMT from a /dev/video0 device, it will just enumerate a hardware functionality, with is constant for a given hardware piece.
The way it works is that userspace do something like:
	int ret = 0;

	for (i = 0; ret == 0; i++) {
		ret = ioctl(VIDIOC_ENUM_FMT, ...);
	}
in order to read an entire const table.
Usually, it doesn't require any special privilege to call this ioctl, but, even if someone changes its permission to 0x400, a simple lsusb output is enough to know what hardware model is there. A lsmod or cat /proc/modules) also tells that the tm6000 module was loaded, with is a very good hint that the tm6000 is there or was there in the past.
In the specific case of tm6000, all hardware supports exactly the same formats, as this is usually defined per-driver. So, a quick look at the driver is enough to know exactly what the ioctl would answer. Also, the net is full of other resources that would allow anyone to get the supported formats for a piece of hardware.
Even assuming that the OS doesn't have lsusb, that /proc is not mounted, that /dev/video0 require special permissions, that the potential attacker doesn't have physical access to the equipment (in order to see if an USB board is plugged), etc... What possible harm he could do by identifying a hardware feature?
Similar notes for the other patches to drivers/media in this
series: let's not just start adding bloatware where not needed.
Please notice that I'm fine if you want to submit potential Spectre variant 1 fixups, but if you're willing to do so, please provide an explanation about the potential threat scenarios that you're identifying at the code.

Quoted 7 lines

Dan,
It probably makes sense to have somewhere at smatch a place where we could explicitly mark the false-positives, in order to avoid use to receive patches that would just add an extra delay where it is not needed.

I see I've missed some obvious things that you've pointed out here. I'll mark these warnings as False Positives and take your points into account for the analysis of the rest of the Spectre issues reported by Smatch.

Sorry for the noise and thanks for the feedback.

Thanks
--
Gustavo

Mauro Carvalho Chehab

maintainer

2018-04-23 19:17 UTC #4 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Em Mon, 23 Apr 2018 14:11:02 -0500
"Gustavo A. R. Silva" <[email protected]> escreveu:

Quoted 89 lines · Mauro Carvalho Chehab

Quoted 88 lines
Em Mon, 23 Apr 2018 12:38:03 -0500
"Gustavo A. R. Silva" <[email protected]> escreveu:
Quoted 35 lines
f->index can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.
Smatch warning:
drivers/media/usb/tm6000/tm6000-video.c:879 vidioc_enum_fmt_vid_cap() warn: potential spectre issue 'format'
Fix this by sanitizing f->index before using it to index array _format_
Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1].
[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
Cc [email protected]
Reported-by Dan Carpenter <[email protected]>
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
  drivers/media/usb/tm6000/tm6000-video.c | 2 ++
  1 file changed, 2 insertions(+)
drivers/media/usb/tm6000/tm6000-video.c +1 -0
index b2399d4..d701027 100644
@@ -26,6 +26,7 @@
  #include <linux/kthread.h>
  #include <linux/highmem.h>
  #include <linux/freezer.h>
+#include <linux/nospec.h>
 
  #include "tm6000-regs.h"
  #include "tm6000.h"
drivers/media/usb/tm6000/tm6000-video.c static int vidioc_enum_fmt_vid_cap(struct file *file, void *priv, · line 879
Quoted 4 lines
drivers/media/usb/tm6000/tm6000-video.c +1 -0
@@ -875,6 +876,7 @@ static int vidioc_enum_fmt_vid_cap(struct file *file, void  *priv,
  	if (f->index >= ARRAY_SIZE(format))
  		return -EINVAL;
 
+	f->index = array_index_nospec(f->index, ARRAY_SIZE(format));  
Please enlighten me: how do you think this could be exploited?
When an application calls VIDIOC_ENUM_FMT from a /dev/video0 device, it will just enumerate a hardware functionality, with is constant for a given hardware piece.
The way it works is that userspace do something like:
	int ret = 0;

	for (i = 0; ret == 0; i++) {
		ret = ioctl(VIDIOC_ENUM_FMT, ...);
	}
in order to read an entire const table.
Usually, it doesn't require any special privilege to call this ioctl, but, even if someone changes its permission to 0x400, a simple lsusb output is enough to know what hardware model is there. A lsmod or cat /proc/modules) also tells that the tm6000 module was loaded, with is a very good hint that the tm6000 is there or was there in the past.
In the specific case of tm6000, all hardware supports exactly the same formats, as this is usually defined per-driver. So, a quick look at the driver is enough to know exactly what the ioctl would answer. Also, the net is full of other resources that would allow anyone to get the supported formats for a piece of hardware.
Even assuming that the OS doesn't have lsusb, that /proc is not mounted, that /dev/video0 require special permissions, that the potential attacker doesn't have physical access to the equipment (in order to see if an USB board is plugged), etc... What possible harm he could do by identifying a hardware feature?
Similar notes for the other patches to drivers/media in this
series: let's not just start adding bloatware where not needed.
Please notice that I'm fine if you want to submit potential Spectre variant 1 fixups, but if you're willing to do so, please provide an explanation about the potential threat scenarios that you're identifying at the code.
Dan,

Quoted 8 lines

Quoted 5 lines
It probably makes sense to have somewhere at smatch a place where we could explicitly mark the false-positives, in order to avoid use to receive patches that would just add an extra delay where it is not needed.
I see I've missed some obvious things that you've pointed out here. I'll mark these warnings as False Positives and take your points into account for the analysis of the rest of the Spectre issues reported by Smatch.

Thanks, I 'll mark this series as rejected at patchwork.linuxtv.org. Please feel free to resubmit any patch if they represent a real threat, adding a corresponding description about the threat scenario at the body of the e-mail.

Quoted 1 line

Sorry for the noise and thanks for the feedback.

Anytime.

Thanks,
Mauro

Gustavo A. R. Silva

author

2018-04-23 19:44 UTC #5 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Quoted 97 lines · Mauro Carvalho Chehab

Em Mon, 23 Apr 2018 14:11:02 -0500
"Gustavo A. R. Silva" <[email protected]> escreveu:
Quoted 94 lines · Mauro Carvalho Chehab
Quoted 93 lines
Em Mon, 23 Apr 2018 12:38:03 -0500
"Gustavo A. R. Silva" <[email protected]> escreveu:
Quoted 35 lines
f->index can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.
Smatch warning:
drivers/media/usb/tm6000/tm6000-video.c:879 vidioc_enum_fmt_vid_cap() warn: potential spectre issue 'format'
Fix this by sanitizing f->index before using it to index array _format_
Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1].
[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
Cc [email protected]
Reported-by Dan Carpenter <[email protected]>
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
   drivers/media/usb/tm6000/tm6000-video.c | 2 ++
   1 file changed, 2 insertions(+)
drivers/media/usb/tm6000/tm6000-video.c +1 -0
index b2399d4..d701027 100644
@@ -26,6 +26,7 @@
   #include <linux/kthread.h>
   #include <linux/highmem.h>
   #include <linux/freezer.h>
+#include <linux/nospec.h>
 
   #include "tm6000-regs.h"
   #include "tm6000.h"
drivers/media/usb/tm6000/tm6000-video.c static int vidioc_enum_fmt_vid_cap(struct file *file, void *priv, · line 879
Quoted 4 lines
drivers/media/usb/tm6000/tm6000-video.c +1 -0
@@ -875,6 +876,7 @@ static int vidioc_enum_fmt_vid_cap(struct file *file, void  *priv,
   	if (f->index >= ARRAY_SIZE(format))
   		return -EINVAL;
 
+	f->index = array_index_nospec(f->index, ARRAY_SIZE(format));
Please enlighten me: how do you think this could be exploited?
When an application calls VIDIOC_ENUM_FMT from a /dev/video0 device, it will just enumerate a hardware functionality, with is constant for a given hardware piece.
The way it works is that userspace do something like:
	int ret = 0;

	for (i = 0; ret == 0; i++) {
		ret = ioctl(VIDIOC_ENUM_FMT, ...);
	}
in order to read an entire const table.
Usually, it doesn't require any special privilege to call this ioctl, but, even if someone changes its permission to 0x400, a simple lsusb output is enough to know what hardware model is there. A lsmod or cat /proc/modules) also tells that the tm6000 module was loaded, with is a very good hint that the tm6000 is there or was there in the past.
In the specific case of tm6000, all hardware supports exactly the same formats, as this is usually defined per-driver. So, a quick look at the driver is enough to know exactly what the ioctl would answer. Also, the net is full of other resources that would allow anyone to get the supported formats for a piece of hardware.
Even assuming that the OS doesn't have lsusb, that /proc is not mounted, that /dev/video0 require special permissions, that the potential attacker doesn't have physical access to the equipment (in order to see if an USB board is plugged), etc... What possible harm he could do by identifying a hardware feature?
Similar notes for the other patches to drivers/media in this
series: let's not just start adding bloatware where not needed.
Please notice that I'm fine if you want to submit potential Spectre variant 1 fixups, but if you're willing to do so, please provide an explanation about the potential threat scenarios that you're identifying at the code.
Dan,
It probably makes sense to have somewhere at smatch a place where we could explicitly mark the false-positives, in order to avoid use to receive patches that would just add an extra delay where it is not needed.

Quoted 9 lines

Quoted 3 lines
I see I've missed some obvious things that you've pointed out here. I'll mark these warnings as False Positives and take your points into account for the analysis of the rest of the Spectre issues reported by Smatch.
Thanks, I 'll mark this series as rejected at patchwork.linuxtv.org. Please feel free to resubmit any patch if they represent a real threat, adding a corresponding description about the threat scenario at the body of the e-mail.

Yeah. I got it.

Quoted 4 lines

Quoted 1 line
Sorry for the noise and thanks for the feedback.
Anytime.

Much appreciated. :)

Thanks
--
Gustavo

Gustavo A. R. Silva

author

2018-04-26 21:42 UTC #6 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Hi Mauro,

Quoted 11 lines · Mauro Carvalho Chehab

Em Mon, 23 Apr 2018 14:11:02 -0500
Thanks, I 'll mark this series as rejected at patchwork.linuxtv.org. Please feel free to resubmit any patch if they represent a real threat, adding a corresponding description about the threat scenario at the body of the e-mail.
Quoted 1 line
Sorry for the noise and thanks for the feedback.
Anytime.

I noticed you changed the status of this series from rejected to new.

Also, there are other similar issues in media/pci/

I can write proper patches for all of them if you agree those are not False Positives:

drivers/media/pci/cx18/cx18-ioctl.c +4 -1

index 80b902b..63f4388 100644
@@ -36,6 +36,8 @@
 #include <media/tveeprom.h>
 #include <media/v4l2-event.h>
 
+#include <linux/nospec.h>
+
 u16 cx18_service2vbi(int type)
 {
        switch (type) {

@@ -488,8 +490,9 @@ static int cx18_enum_fmt_vid_cap(struct file *file, void *fh,
                },
        };
 
-       if (fmt->index > ARRAY_SIZE(formats) - 1)
+       if (fmt->index >= ARRAY_SIZE(formats))
                return -EINVAL;
+       fmt->index = array_index_nospec(fmt->index, ARRAY_SIZE(formats));
        *fmt = formats[fmt->index];
        return 0;
 }

drivers/media/pci/saa7134/saa7134-video.c +4 -0

index 1a50ec9..d93cf09 100644
@@ -30,6 +30,8 @@
 #include <media/v4l2-event.h>
 #include <media/i2c/saa6588.h>
 
+#include <linux/nospec.h>
+
 /* ------------------------------------------------------------------ */
 
 unsigned int video_debug;

@@ -1819,6 +1821,8 @@ static int saa7134_enum_fmt_vid_cap(struct file *file, void  *priv,
        if (f->index >= FORMATS)
                return -EINVAL;
 
+       f->index = array_index_nospec(f->index, FORMATS);
+
        strlcpy(f->description, formats[f->index].name,
                sizeof(f->description));

drivers/media/pci/tw68/tw68-video.c +0 -0

index 8c1f4a0..a6cfb4b 100644

--- a/drivers/media/pci/tw68/tw68-video.c
#include <media/v4l2-event.h>
#include <media/videobuf2-dma-sg.h>

+#include <linux/nospec.h>
+
#include "tw68.h"
#include "tw68-reg.h"

@@ -789,6 +791,8 @@ static int tw68_enum_fmt_vid_cap(struct file *file, void *priv,

        if (f->index >= FORMATS)
                return -EINVAL;

+ f->index = array_index_nospec(f->index, FORMATS);
+

        strlcpy(f->description, formats[f->index].name,
                sizeof(f->description));

drivers/media/pci/tw686x/tw686x-video.c +2 -0

index c3fafa9..281d722 100644
@@ -25,6 +25,8 @@
 #include "tw686x.h"
 #include "tw686x-regs.h"
 
+#include <linux/nospec.h>
+
 #define TW686X_INPUTS_PER_CH           4
 #define TW686X_VIDEO_WIDTH             720
 #define TW686X_VIDEO_HEIGHT(id)                ((id & V4L2_STD_525_60)

? 480 : 576)
@@ -981,6 +983,7 @@ static int tw686x_enum_fmt_vid_cap(struct file *file, void *priv,

 {
        if (f->index >= ARRAY_SIZE(formats))
                return -EINVAL;
+       f->index = array_index_nospec(f->index, ARRAY_SIZE(formats));
        f->pixelformat = formats[f->index].fourcc;
        return 0;

}

Thanks
--
Gustavo

Mauro Carvalho Chehab

2018-04-26 23:42 UTC #7 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Em Thu, 26 Apr 2018 16:41:56 -0500
"Gustavo A. R. Silva" <[email protected]> escreveu:

Quoted 10 lines

Hi Mauro,
Quoted 7 lines · Mauro Carvalho Chehab
Em Mon, 23 Apr 2018 14:11:02 -0500
Thanks, I 'll mark this series as rejected at patchwork.linuxtv.org. Please feel free to resubmit any patch if they represent a real threat, adding a corresponding description about the threat scenario at the body of the e-mail.

Quoted 6 lines

Quoted 4 lines
Quoted 1 line
Sorry for the noise and thanks for the feedback.
Anytime.
I noticed you changed the status of this series from rejected to new.

Yes.

Quoted 1 line

Also, there are other similar issues in media/pci/

Well, the issues will be there everywhere on all media drivers.

I marked your patches because I need to study it carefully, after Peter's explanations. My plan is to do it next week. Still not sure if the approach you took is the best one or not.

As I said, one possibility is to change the way v4l2-core handles VIDIOC_ENUM_foo ioctls, but that would be make harder to -stable backports.

I need a weekend to sleep on it.

Quoted 102 lines

I can write proper patches for all of them if you agree those are not False Positives:

drivers/media/pci/cx18/cx18-ioctl.c +4 -1

index 80b902b..63f4388 100644
@@ -36,6 +36,8 @@
  #include <media/tveeprom.h>
  #include <media/v4l2-event.h>
 
+#include <linux/nospec.h>
+
  u16 cx18_service2vbi(int type)
  {
         switch (type) {

@@ -488,8 +490,9 @@ static int cx18_enum_fmt_vid_cap(struct file *file, 
 void *fh,
                 },
         };
 
-       if (fmt->index > ARRAY_SIZE(formats) - 1)
+       if (fmt->index >= ARRAY_SIZE(formats))
                 return -EINVAL;
+       fmt->index = array_index_nospec(fmt->index, ARRAY_SIZE(formats));
         *fmt = formats[fmt->index];
         return 0;

drivers/media/pci/saa7134/saa7134-video.c +4 -0

index 1a50ec9..d93cf09 100644
@@ -30,6 +30,8 @@
  #include <media/v4l2-event.h>
  #include <media/i2c/saa6588.h>
 
+#include <linux/nospec.h>
+
  /* ------------------------------------------------------------------ */
 
  unsigned int video_debug;

@@ -1819,6 +1821,8 @@ static int saa7134_enum_fmt_vid_cap(struct file 
 *file, void  *priv,
         if (f->index >= FORMATS)
                 return -EINVAL;
 
+       f->index = array_index_nospec(f->index, FORMATS);
+
         strlcpy(f->description, formats[f->index].name,
                 sizeof(f->description));

drivers/media/pci/tw68/tw68-video.c +4 -1

index 8c1f4a0..a6cfb4b 100644
--- a/drivers/media/pci/tw68/tw68-video.c
  #include <media/v4l2-event.h>
  #include <media/videobuf2-dma-sg.h>
 
+#include <linux/nospec.h>
+
  #include "tw68.h"
  #include "tw68-reg.h"

@@ -789,6 +791,8 @@ static int tw68_enum_fmt_vid_cap(struct file *file, 
 void  *priv,
         if (f->index >= FORMATS)
                 return -EINVAL;
 
+       f->index = array_index_nospec(f->index, FORMATS);
+
         strlcpy(f->description, formats[f->index].name,
                 sizeof(f->description));

drivers/media/pci/tw686x/tw686x-video.c +2 -0

index c3fafa9..281d722 100644
@@ -25,6 +25,8 @@
  #include "tw686x.h"
  #include "tw686x-regs.h"
 
+#include <linux/nospec.h>
+
  #define TW686X_INPUTS_PER_CH           4
  #define TW686X_VIDEO_WIDTH             720
  #define TW686X_VIDEO_HEIGHT(id)                ((id & V4L2_STD_525_60)

? 480 : 576)

drivers/media/pci/tw686x/tw686x-video.c +1 -0

@@ -981,6 +983,7 @@ static int tw686x_enum_fmt_vid_cap(struct file 
 *file, void *priv,
  {
         if (f->index >= ARRAY_SIZE(formats))
                 return -EINVAL;
+       f->index = array_index_nospec(f->index, ARRAY_SIZE(formats));
         f->pixelformat = formats[f->index].fourcc;
         return 0;

Quoted 3 lines

Thanks
--
Gustavo

Thanks,
Mauro

Gustavo A. R. Silva

author

2018-05-15 03:53 UTC #8 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Hi Mauro,

Quoted 13 lines · Mauro Carvalho Chehab

Quoted 2 lines
I noticed you changed the status of this series from rejected to new.
Yes.
Quoted 1 line
Also, there are other similar issues in media/pci/
Well, the issues will be there everywhere on all media drivers.
I marked your patches because I need to study it carefully, after Peter's explanations. My plan is to do it next week. Still not sure if the approach you took is the best one or not.

Quoted 6 lines

As I said, one possibility is to change the way v4l2-core handles VIDIOC_ENUM_foo ioctls, but that would be make harder to -stable backports.
I need a weekend to sleep on it.

I'm curious about how you finally resolved to handle these issues.

I noticed Smatch is no longer reporting them.

Thanks
--
Gustavo

Mauro Carvalho Chehab

2018-05-15 12:00 UTC #9 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Em Mon, 14 May 2018 22:31:37 -0500
"Gustavo A. R. Silva" <[email protected]> escreveu:

Quoted 21 lines

Hi Mauro,
Quoted 17 lines · Mauro Carvalho Chehab
Quoted 2 lines
I noticed you changed the status of this series from rejected to new.
Yes.
Quoted 1 line
Also, there are other similar issues in media/pci/
Well, the issues will be there everywhere on all media drivers.
I marked your patches because I need to study it carefully, after Peter's explanations. My plan is to do it next week. Still not sure if the approach you took is the best one or not.
As I said, one possibility is to change the way v4l2-core handles VIDIOC_ENUM_foo ioctls, but that would be make harder to -stable backports.

Quoted 6 lines

Quoted 2 lines
I need a weekend to sleep on it.
I'm curious about how you finally resolved to handle these issues.
I noticed Smatch is no longer reporting them.

There was no direct fix for it, but maybe this patch has something to do with the smatch error report cleanup:

commit 3ad3b7a2ebaefae37a7eafed0779324987ca5e56

Author: Sami Tolvanen <[email protected]>
Date:   Tue May 8 13:56:12 2018 -0400

media: v4l2-ioctl: replace IOCTL_INFO_STD with stub functions

This change removes IOCTL_INFO_STD and adds stub functions where needed using the DEFINE_V4L_STUB_FUNC macro. This fixes indirect call mismatches with Control-Flow Integrity, caused by calling standard ioctls using a function pointer that doesn't match the function type.

Signed-off-by Sami Tolvanen <[email protected]>

Signed-off-by Hans Verkuil <[email protected]>

Signed-off-by Mauro Carvalho Chehab <[email protected]>

Quoted 4 lines

Thanks
--
Gustavo

Thanks,
Mauro

Dan Carpenter

2018-05-15 14:17 UTC #10 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Quoted 40 lines · Mauro Carvalho Chehab

Em Mon, 14 May 2018 22:31:37 -0500
"Gustavo A. R. Silva" <[email protected]> escreveu:
Quoted 21 lines
Hi Mauro,
Quoted 17 lines · Mauro Carvalho Chehab
Quoted 2 lines
I noticed you changed the status of this series from rejected to new.
Yes.
Quoted 1 line
Also, there are other similar issues in media/pci/
Well, the issues will be there everywhere on all media drivers.
I marked your patches because I need to study it carefully, after Peter's explanations. My plan is to do it next week. Still not sure if the approach you took is the best one or not.
As I said, one possibility is to change the way v4l2-core handles VIDIOC_ENUM_foo ioctls, but that would be make harder to -stable backports.
Quoted 6 lines
Quoted 2 lines
I need a weekend to sleep on it.
I'm curious about how you finally resolved to handle these issues.
I noticed Smatch is no longer reporting them.
There was no direct fix for it, but maybe this patch has something to do with the smatch error report cleanup:
commit 3ad3b7a2ebaefae37a7eafed0779324987ca5e56
Author: Sami Tolvanen <[email protected]>
Date:   Tue May 8 13:56:12 2018 -0400
media: v4l2-ioctl: replace IOCTL_INFO_STD with stub functions

Quoted 9 lines

This change removes IOCTL_INFO_STD and adds stub functions where needed using the DEFINE_V4L_STUB_FUNC macro. This fixes indirect call mismatches with Control-Flow Integrity, caused by calling standard ioctls using a function pointer that doesn't match the function type.
Signed-off-by Sami Tolvanen <[email protected]>
Signed-off-by Hans Verkuil <[email protected]>
Signed-off-by Mauro Carvalho Chehab <[email protected]>

Possibly... There was an ancient bug in Smatch's function pointer handling. I just pushed a fix for it now so the warning is there on linux-next.

regards,
dan carpenter

Gustavo A. R. Silva

author

2018-05-15 17:49 UTC #11 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Quoted 19 lines · Dan Carpenter

Quoted 19 lines
Quoted 4 lines
I'm curious about how you finally resolved to handle these issues.
I noticed Smatch is no longer reporting them.
There was no direct fix for it, but maybe this patch has something to do with the smatch error report cleanup:
commit 3ad3b7a2ebaefae37a7eafed0779324987ca5e56
Author: Sami Tolvanen <[email protected]>
Date:   Tue May 8 13:56:12 2018 -0400
media: v4l2-ioctl: replace IOCTL_INFO_STD with stub functions
This change removes IOCTL_INFO_STD and adds stub functions where needed using the DEFINE_V4L_STUB_FUNC macro. This fixes indirect call mismatches with Control-Flow Integrity, caused by calling standard ioctls using a function pointer that doesn't match the function type.

Quoted 4 lines

Quoted 4 lines
Signed-off-by Sami Tolvanen <[email protected]>
Signed-off-by Hans Verkuil <[email protected]>
Signed-off-by Mauro Carvalho Chehab <[email protected]>

Thanks, Mauro.

Quoted 5 lines

Possibly... There was an ancient bug in Smatch's function pointer handling. I just pushed a fix for it now so the warning is there on linux-next.

Dan,

These are all the Spectre media issues I see smatch is reporting in linux-next-20180515:

drivers/media/cec/cec-pin-error-inj.c:170 cec_pin_error_inj_parse_line() warn: potential spectre issue 'pin->error_inj_args' drivers/media/dvb-core/dvb_ca_en50221.c:1479 dvb_ca_en50221_io_write() warn: potential spectre issue 'ca->slot_info' (local cap) drivers/media/dvb-core/dvb_net.c:252 handle_one_ule_extension() warn: potential spectre issue 'p->ule_next_hdr'

I pulled the latest changes from the smatch repository and compiled it.

I'm running smatch v0.5.0-4459-g2f66d40 now. Is this the latest version?

I wonder if there is anything I might be missing.

Thanks
--
Gustavo

Mauro Carvalho Chehab

2018-05-15 19:00 UTC #12 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Em Tue, 15 May 2018 12:29:10 -0500
"Gustavo A. R. Silva" <[email protected]> escreveu:

Quoted 33 lines · Dan Carpenter

Quoted 19 lines
Quoted 19 lines
Quoted 4 lines
I'm curious about how you finally resolved to handle these issues.
I noticed Smatch is no longer reporting them.
There was no direct fix for it, but maybe this patch has something to do with the smatch error report cleanup:
commit 3ad3b7a2ebaefae37a7eafed0779324987ca5e56
Author: Sami Tolvanen <[email protected]>
Date:   Tue May 8 13:56:12 2018 -0400
media: v4l2-ioctl: replace IOCTL_INFO_STD with stub functions
This change removes IOCTL_INFO_STD and adds stub functions where needed using the DEFINE_V4L_STUB_FUNC macro. This fixes indirect call mismatches with Control-Flow Integrity, caused by calling standard ioctls using a function pointer that doesn't match the function type.
Quoted 4 lines
Quoted 4 lines
Signed-off-by Sami Tolvanen <[email protected]>
Signed-off-by Hans Verkuil <[email protected]>
Signed-off-by Mauro Carvalho Chehab <[email protected]>
Thanks, Mauro.
Quoted 5 lines
Possibly... There was an ancient bug in Smatch's function pointer handling. I just pushed a fix for it now so the warning is there on linux-next.

Quoted 4 lines

Dan,
These are all the Spectre media issues I see smatch is reporting in linux-next-20180515:

Yeah, that's the same I'm getting from media upstream.

Quoted 2 lines

drivers/media/cec/cec-pin-error-inj.c:170 cec_pin_error_inj_parse_line()
warn: potential spectre issue 'pin->error_inj_args'

This one seems a false positive, as the index var is u8 and the array has 256 elements, as the userspace input from 'op' is initialized with:

	u8 v;
	u32 op;

	if (!kstrtou8(token, 0, &v))
		op = v;

Quoted 2 lines

drivers/media/dvb-core/dvb_ca_en50221.c:1479 dvb_ca_en50221_io_write()
warn: potential spectre issue 'ca->slot_info' (local cap)

This one seems a real issue to me. Sent a patch for it.

Quoted 2 lines

drivers/media/dvb-core/dvb_net.c:252 handle_one_ule_extension() warn:
potential spectre issue 'p->ule_next_hdr'

I failed to see what's wrong here, or if this is exploited.

Quoted 6 lines

I pulled the latest changes from the smatch repository and compiled it.
I'm running smatch v0.5.0-4459-g2f66d40 now. Is this the latest version?
I wonder if there is anything I might be missing.

Here, I'm at this commit:

commit 2f66d40cbf57b0bd581fe75447d2a8625fc7bb1d (origin/master, origin/HEAD)

Author: Dan Carpenter <[email protected]>
Date:   Tue May 15 16:35:20 2018 +0300

db: make call_implies rows unique

Plus the diff below (that won't affect Spectre errors).

Regards,
Mauro

Quoted 5 lines

Thanks
--
Gustavo

check_missing_break.c +1 -1

index 434b7283fc94..5bba6e919521 100644
@@ -73,7 +73,7 @@ static void print_missing_break(struct expression *expr)
 	last_print_expr = get_switch_expr();
 
 	name = expr_to_var(expr);
-	sm_msg("warn: missing break? reassigning '%s'", name);
+//	sm_msg("warn: missing break? reassigning '%s'", name);
 	free_string(name);
 }

smatch_flow.c +1 -2

index dc0e78824370..cd72a9ded375 100644
@@ -1005,8 +1005,7 @@ void __split_stmt(struct statement *stmt)
 
 		__bail_on_rest_of_function = 1;
 		final_pass = 1;
-		sm_msg("Function too hairy.  Giving up. %lu seconds",
-		       stop.tv_sec - fn_start_time.tv_sec);
+		sm_msg("__split_smt: function too hairy.  Giving up.");
 		fake_a_return();
 		final_pass = 0;  /* turn off sm_msg() from here */
 		return;

smatch_implied.c +1 -1

index 3588816361fe..f3ccd4b6d79e 100644
@@ -594,7 +594,7 @@ static void separate_and_filter(struct sm_state *sm, int comparison, struct rang
 
 	gettimeofday(&time_after, NULL);
 	sec = time_after.tv_sec - time_before.tv_sec;
-	if (sec > 20) {
+	if (sec > 60) {
 		sm->nr_children = 4000;
 		sm_msg("Function too hairy.  Ignoring implications after %d seconds.", sec);
 	}

smatch_slist.c +4 -2

index e1eb1b999b2a..2f8ba34a4b9a 100644
@@ -237,12 +237,14 @@ char *alloc_sname(const char *str)
 int out_of_memory(void)
 {
 	/*
-	 * I decided to use 50M here based on trial and error.
+	 * I decided to use 6GB here based on trial and error.
 	 * It works out OK for the kernel and so it should work
 	 * for most other projects as well.
 	 */
-	if (sm_state_counter * sizeof(struct sm_state) >= 100000000)
+	if (sm_state_counter * sizeof(struct sm_state) >= 6000000000) {
+		sm_msg("Out of memory");
 		return 1;
+	}
 	return 0;
 }

Thanks,
Mauro

Dan Carpenter

2018-05-16 13:11 UTC #13 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Quoted 9 lines · Mauro Carvalho Chehab

Yeah, that's the same I'm getting from media upstream.
Quoted 2 lines
drivers/media/cec/cec-pin-error-inj.c:170 cec_pin_error_inj_parse_line()
warn: potential spectre issue 'pin->error_inj_args'
This one seems a false positive, as the index var is u8 and the array has 256 elements, as the userspace input from 'op' is initialized with:

Quoted 6 lines

	u8 v;
	u32 op;

	if (!kstrtou8(token, 0, &v))
		op = v;

It's hard to silence this because Smatch stores the current user controlled range list, not what it was initially. I wrote all this code to detect bounds checking errors, so there wasn't any need to save the range list before the bounds check. Since "op" is a u32, I can't even go by the type of the index....

Quoted 9 lines

Quoted 2 lines
drivers/media/dvb-core/dvb_ca_en50221.c:1479 dvb_ca_en50221_io_write()
warn: potential spectre issue 'ca->slot_info' (local cap)
This one seems a real issue to me. Sent a patch for it.
Quoted 2 lines
drivers/media/dvb-core/dvb_net.c:252 handle_one_ule_extension() warn:
potential spectre issue 'p->ule_next_hdr'
I failed to see what's wrong here, or if this is exploited.

Oh... Huh. This is a bug in smatch. That line looks like:

	p->ule_sndu_type = ntohs(*(__be16 *)(p->ule_next_hdr + ((p->ule_dbit ? 2 : 3) * ETH_ALEN)));

Smatch see the ntohs() and marks everything inside it as untrusted network data. I'll fix this.

regards,
dan carpenter

Mauro Carvalho Chehab

2018-05-16 13:37 UTC #14 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Em Wed, 16 May 2018 16:11:08 +0300
Dan Carpenter <[email protected]> escreveu:

Quoted 17 lines · Mauro Carvalho Chehab

Quoted 9 lines
Yeah, that's the same I'm getting from media upstream.
Quoted 2 lines
drivers/media/cec/cec-pin-error-inj.c:170 cec_pin_error_inj_parse_line()
warn: potential spectre issue 'pin->error_inj_args'
This one seems a false positive, as the index var is u8 and the array has 256 elements, as the userspace input from 'op' is initialized with:
Quoted 6 lines
	u8 v;
	u32 op;

	if (!kstrtou8(token, 0, &v))
		op = v;

Quoted 5 lines

It's hard to silence this because Smatch stores the current user controlled range list, not what it was initially. I wrote all this code to detect bounds checking errors, so there wasn't any need to save the range list before the bounds check. Since "op" is a u32, I can't even go by the type of the index....

Yeah, I was thinking that is would be harder to clean this up on smatch. I proposed a patch to the ML that simplifies the logic, making easier for both humans and Smatch to better understand how the arrays are indexed.

Quoted 9 lines

Quoted 9 lines
Quoted 3 lines
drivers/media/dvb-core/dvb_ca_en50221.c:1479 dvb_ca_en50221_io_write()
warn: potential spectre issue 'ca->slot_info' (local cap)
This one seems a real issue to me. Sent a patch for it.
Quoted 2 lines
drivers/media/dvb-core/dvb_net.c:252 handle_one_ule_extension() warn:
potential spectre issue 'p->ule_next_hdr'

Quoted 8 lines

Quoted 1 line
I failed to see what's wrong here, or if this is exploited.
Oh... Huh. This is a bug in smatch. That line looks like:
	p->ule_sndu_type = ntohs(*(__be16 *)(p->ule_next_hdr + ((p->ule_dbit ? 2 : 3) * ETH_ALEN)));
Smatch see the ntohs() and marks everything inside it as untrusted network data. I'll fix this.

Thanks!

Regards,
Mauro

Dan Carpenter

2018-05-15 19:39 UTC #15 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

https://patchwork.linuxtv.org/project/linux-media/list/?submitter=7277

Quoted 45 lines · Gustavo A. R. Silva

Quoted 12 lines · Dan Carpenter
Quoted 12 lines
Quoted 4 lines
I'm curious about how you finally resolved to handle these issues.
I noticed Smatch is no longer reporting them.
There was no direct fix for it, but maybe this patch has something to do with the smatch error report cleanup:
commit 3ad3b7a2ebaefae37a7eafed0779324987ca5e56
Author: Sami Tolvanen <[email protected]>
Date:   Tue May 8 13:56:12 2018 -0400
Quoted 9 lines
Quoted 9 lines
media: v4l2-ioctl: replace IOCTL_INFO_STD with stub functions This change removes IOCTL_INFO_STD and adds stub functions where needed using the DEFINE_V4L_STUB_FUNC macro. This fixes indirect call mismatches with Control-Flow Integrity, caused by calling standard ioctls using a function pointer that doesn't match the function type.
Signed-off-by Sami Tolvanen <[email protected]>
Signed-off-by Hans Verkuil <[email protected]>
Signed-off-by Mauro Carvalho Chehab <[email protected]>
Thanks, Mauro.
Quoted 5 lines
Possibly... There was an ancient bug in Smatch's function pointer handling. I just pushed a fix for it now so the warning is there on linux-next.
Dan,
These are all the Spectre media issues I see smatch is reporting in linux-next-20180515:
drivers/media/cec/cec-pin-error-inj.c:170 cec_pin_error_inj_parse_line()
warn: potential spectre issue 'pin->error_inj_args' drivers/media/dvb-core/dvb_ca_en50221.c:1479 dvb_ca_en50221_io_write() warn:
potential spectre issue 'ca->slot_info' (local cap) drivers/media/dvb-core/dvb_net.c:252 handle_one_ule_extension() warn:
potential spectre issue 'p->ule_next_hdr'

Quoted 6 lines

I pulled the latest changes from the smatch repository and compiled it.
I'm running smatch v0.5.0-4459-g2f66d40 now. Is this the latest version?
I wonder if there is anything I might be missing.

You'd need to rebuild the db (possibly twice but definitely once).

regards,
dan carpenter

Gustavo A. R. Silva

author

2018-05-17 01:14 UTC #16 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Quoted 12 lines · Dan Carpenter

Quoted 12 lines
Dan,
These are all the Spectre media issues I see smatch is reporting in linux-next-20180515:
drivers/media/cec/cec-pin-error-inj.c:170 cec_pin_error_inj_parse_line()
warn: potential spectre issue 'pin->error_inj_args' drivers/media/dvb-core/dvb_ca_en50221.c:1479 dvb_ca_en50221_io_write() warn:
potential spectre issue 'ca->slot_info' (local cap) drivers/media/dvb-core/dvb_net.c:252 handle_one_ule_extension() warn:
potential spectre issue 'p->ule_next_hdr'

Quoted 9 lines

Quoted 6 lines
I pulled the latest changes from the smatch repository and compiled it.
I'm running smatch v0.5.0-4459-g2f66d40 now. Is this the latest version?
I wonder if there is anything I might be missing.
You'd need to rebuild the db (possibly twice but definitely once).

Hi Dan,

After rebuilding the db (once), these are all the Spectre media warnings I get:

drivers/media/pci/ddbridge/ddbridge-core.c:233 ddb_redirect() warn: potential spectre issue 'ddbs' drivers/media/pci/ddbridge/ddbridge-core.c:243 ddb_redirect() warn: potential spectre issue 'pdev->port' drivers/media/pci/ddbridge/ddbridge-core.c:252 ddb_redirect() warn: potential spectre issue 'idev->input' drivers/media/dvb-core/dvb_ca_en50221.c:1400 dvb_ca_en50221_io_do_ioctl() warn: potential spectre issue 'ca->slot_info' (local cap) drivers/media/dvb-core/dvb_ca_en50221.c:1479 dvb_ca_en50221_io_write() warn: potential spectre issue 'ca->slot_info' (local cap) drivers/media/dvb-core/dvb_net.c:252 handle_one_ule_extension() warn: potential spectre issue 'p->ule_next_hdr' drivers/media/dvb-core/dvb_net.c:1483 dvb_net_do_ioctl() warn: potential spectre issue 'dvbnet->device' (local cap) drivers/media/cec/cec-pin-error-inj.c:170 cec_pin_error_inj_parse_line() warn: potential spectre issue 'pin->error_inj_args'

I just want to double check if you are getting the same output. In case you are getting the same, then what Mauro commented about these issues:

being resolved by commit 3ad3b7a2ebaefae37a7eafed0779324987ca5e56 seems to be correct.

Thanks
--
Gustavo

Gustavo A. R. Silva

author

2018-05-17 10:36 UTC #17 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Quoted 38 lines · Gustavo A. R. Silva

Quoted 12 lines · Dan Carpenter
Quoted 12 lines
Dan,
These are all the Spectre media issues I see smatch is reporting in linux-next-20180515:
drivers/media/cec/cec-pin-error-inj.c:170 cec_pin_error_inj_parse_line()
warn: potential spectre issue 'pin->error_inj_args' drivers/media/dvb-core/dvb_ca_en50221.c:1479 dvb_ca_en50221_io_write() warn:
potential spectre issue 'ca->slot_info' (local cap) drivers/media/dvb-core/dvb_net.c:252 handle_one_ule_extension() warn:
potential spectre issue 'p->ule_next_hdr'
Quoted 9 lines
Quoted 6 lines
I pulled the latest changes from the smatch repository and compiled it.
I'm running smatch v0.5.0-4459-g2f66d40 now. Is this the latest version?
I wonder if there is anything I might be missing.
You'd need to rebuild the db (possibly twice but definitely once).
Hi Dan,
After rebuilding the db (once), these are all the Spectre media warnings I get:
drivers/media/pci/ddbridge/ddbridge-core.c:233 ddb_redirect() warn: potential spectre issue 'ddbs' drivers/media/pci/ddbridge/ddbridge-core.c:243 ddb_redirect() warn: potential spectre issue 'pdev->port' drivers/media/pci/ddbridge/ddbridge-core.c:252 ddb_redirect() warn: potential spectre issue 'idev->input' drivers/media/dvb-core/dvb_ca_en50221.c:1400 dvb_ca_en50221_io_do_ioctl() warn: potential spectre issue 'ca->slot_info' (local cap) drivers/media/dvb-core/dvb_ca_en50221.c:1479 dvb_ca_en50221_io_write() warn: potential spectre issue 'ca->slot_info' (local cap) drivers/media/dvb-core/dvb_net.c:252 handle_one_ule_extension() warn: potential spectre issue 'p->ule_next_hdr' drivers/media/dvb-core/dvb_net.c:1483 dvb_net_do_ioctl() warn: potential spectre issue 'dvbnet->device' (local cap) drivers/media/cec/cec-pin-error-inj.c:170 cec_pin_error_inj_parse_line() warn: potential spectre issue 'pin->error_inj_args'

Quoted 6 lines

I just want to double check if you are getting the same output. In case you are getting the same, then what Mauro commented about these issues:
https://patchwork.linuxtv.org/project/linux-media/list/?submitter=7277
being resolved by commit 3ad3b7a2ebaefae37a7eafed0779324987ca5e56 seems to be correct.

Interesting, I've rebuild the db twice and now I get a total of 75 Spectre warnings in drivers/media

--
Gustavo

Mauro Carvalho Chehab

2018-05-17 11:34 UTC #18 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Em Thu, 17 May 2018 05:36:03 -0500
"Gustavo A. R. Silva" <[email protected]> escreveu:

Quoted 8 lines · Gustavo A. R. Silva

Quoted 5 lines · Dan Carpenter
Quoted 2 lines
You'd need to rebuild the db (possibly twice but definitely once).

How? Here, I just pull from your git tree and do a "make". At most, make clean; make.

Quoted 28 lines

Quoted 28 lines
Quoted 1 line
Hi Dan,
After rebuilding the db (once), these are all the Spectre media warnings I get:
drivers/media/pci/ddbridge/ddbridge-core.c:233 ddb_redirect() warn:
potential spectre issue 'ddbs' drivers/media/pci/ddbridge/ddbridge-core.c:243 ddb_redirect() warn:
potential spectre issue 'pdev->port' drivers/media/pci/ddbridge/ddbridge-core.c:252 ddb_redirect() warn:
potential spectre issue 'idev->input' drivers/media/dvb-core/dvb_ca_en50221.c:1400 dvb_ca_en50221_io_do_ioctl() warn: potential spectre issue 'ca->slot_info' (local cap) drivers/media/dvb-core/dvb_ca_en50221.c:1479 dvb_ca_en50221_io_write()
warn: potential spectre issue 'ca->slot_info' (local cap) drivers/media/dvb-core/dvb_net.c:252 handle_one_ule_extension() warn:
potential spectre issue 'p->ule_next_hdr' drivers/media/dvb-core/dvb_net.c:1483 dvb_net_do_ioctl() warn: potential spectre issue 'dvbnet->device' (local cap) drivers/media/cec/cec-pin-error-inj.c:170 cec_pin_error_inj_parse_line()
warn: potential spectre issue 'pin->error_inj_args'
I just want to double check if you are getting the same output. In case you are getting the same, then what Mauro commented about these issues:

Quoted 8 lines

Quoted 5 lines
https://patchwork.linuxtv.org/project/linux-media/list/?submitter=7277
being resolved by commit 3ad3b7a2ebaefae37a7eafed0779324987ca5e56 seems to be correct.
Interesting, I've rebuild the db twice and now I get a total of 75 Spectre warnings in drivers/media

That makes more sense to me, as the same pattern is used by almost all VIDIOC_ENUM_foo ioctls.

Thanks,
Mauro

Mauro Carvalho Chehab

2018-05-17 11:43 UTC #19 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Em Thu, 17 May 2018 08:34:40 -0300
Mauro Carvalho Chehab <[email protected]> escreveu:

Quoted 8 lines

Em Thu, 17 May 2018 05:36:03 -0500
"Gustavo A. R. Silva" <[email protected]> escreveu:
Quoted 5 lines · Gustavo A. R. Silva
Quoted 2 lines

Quoted 6 lines

Quoted 3 lines
Quoted 3 lines · Dan Carpenter
Quoted 2 lines
You'd need to rebuild the db (possibly twice but definitely once).
How? Here, I just pull from your git tree and do a "make". At most, make clean; make.

Never mind. Found it using grep. I'm running this:

make allyesconfig /devel/smatch/smatch_scripts/build_kernel_data.sh /devel/smatch/smatch_scripts/build_kernel_data.sh

Quoted 35 lines

Quoted 35 lines
Quoted 34 lines
Quoted 2 lines
Hi Dan,
After rebuilding the db (once), these are all the Spectre media warnings I get:
drivers/media/pci/ddbridge/ddbridge-core.c:233 ddb_redirect() warn:
potential spectre issue 'ddbs' drivers/media/pci/ddbridge/ddbridge-core.c:243 ddb_redirect() warn:
potential spectre issue 'pdev->port' drivers/media/pci/ddbridge/ddbridge-core.c:252 ddb_redirect() warn:
potential spectre issue 'idev->input' drivers/media/dvb-core/dvb_ca_en50221.c:1400 dvb_ca_en50221_io_do_ioctl() warn: potential spectre issue 'ca->slot_info' (local cap) drivers/media/dvb-core/dvb_ca_en50221.c:1479 dvb_ca_en50221_io_write()
warn: potential spectre issue 'ca->slot_info' (local cap) drivers/media/dvb-core/dvb_net.c:252 handle_one_ule_extension() warn:
potential spectre issue 'p->ule_next_hdr' drivers/media/dvb-core/dvb_net.c:1483 dvb_net_do_ioctl() warn: potential spectre issue 'dvbnet->device' (local cap) drivers/media/cec/cec-pin-error-inj.c:170 cec_pin_error_inj_parse_line()
warn: potential spectre issue 'pin->error_inj_args'
I just want to double check if you are getting the same output. In case you are getting the same, then what Mauro commented about these issues:
https://patchwork.linuxtv.org/project/linux-media/list/?submitter=7277
being resolved by commit 3ad3b7a2ebaefae37a7eafed0779324987ca5e56 seems to be correct.

Quoted 8 lines

Quoted 2 lines
Interesting, I've rebuild the db twice and now I get a total of 75 Spectre warnings in drivers/media
That makes more sense to me, as the same pattern is used by almost all VIDIOC_ENUM_foo ioctls.
Thanks,
Mauro

Thanks,
Mauro

Mauro Carvalho Chehab

2018-05-17 12:13 UTC #20 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Em Thu, 17 May 2018 08:43:24 -0300
Mauro Carvalho Chehab <[email protected]> escreveu:

Quoted 4 lines

Quoted 4 lines
Quoted 3 lines
Quoted 3 lines · Dan Carpenter
Quoted 2 lines
You'd need to rebuild the db (possibly twice but definitely once).

Quoted 8 lines

Quoted 2 lines
How? Here, I just pull from your git tree and do a "make". At most, make clean; make.
Never mind. Found it using grep. I'm running this:
make allyesconfig /devel/smatch/smatch_scripts/build_kernel_data.sh /devel/smatch/smatch_scripts/build_kernel_data.sh

It seems that something is broken... getting this error/warning:

DBD::SQLite::db do failed: unrecognized token: "'end + strlen("
" at /devel/smatch/smatch_scripts/../smatch_data/db/fill_db_sql.pl line 32, <WARNS> line 2938054.

Thanks,
Mauro

Gustavo A. R. Silva

author

2018-05-17 18:08 UTC #21 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Quoted 12 lines · Mauro Carvalho Chehab

Em Thu, 17 May 2018 08:43:24 -0300
Mauro Carvalho Chehab <[email protected]> escreveu:
Quoted 9 lines
Quoted 6 lines
Quoted 3 lines
Quoted 3 lines · Dan Carpenter
Quoted 2 lines
You'd need to rebuild the db (possibly twice but definitely once).
How? Here, I just pull from your git tree and do a "make". At most, make clean; make.
Never mind. Found it using grep. I'm running this:

Quoted 9 lines

Quoted 3 lines
make allyesconfig /devel/smatch/smatch_scripts/build_kernel_data.sh /devel/smatch/smatch_scripts/build_kernel_data.sh
It seems that something is broken... getting this error/warning:
DBD::SQLite::db do failed: unrecognized token: "'end + strlen("
" at /devel/smatch/smatch_scripts/../smatch_data/db/fill_db_sql.pl line 32, <WARNS> line 2938054.

Yep. I get the same warning multiple times.

BTW, Mauro, you sent a patch to fix an spectre v1 issue in this file yesterday: dvb_ca_en50221.c:1480, but it seems there is another instance of the same issue some lines above:

drivers/media/dvb-core/dvb_ca_en50221.c +1 -0

index 1310526..7edd9db 100644
@@ -1398,6 +1398,7 @@ static int dvb_ca_en50221_io_do_ioctl(struct file *file,
 
                info->type = CA_CI_LINK;
                info->flags = 0;
+               slot = array_index_nospec(slot, ca->slot_count + 1);
                sl = &ca->slot_info[slot];
                if ((sl->slot_state != DVB_CA_SLOTSTATE_NONE) &&
                    (sl->slot_state != DVB_CA_SLOTSTATE_INVALID)) {

Thanks
--
Gustavo

Gustavo A. R. Silva

author

2018-05-21 16:19 UTC #22 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Quoted 15 lines · Gustavo A. R. Silva

BTW, Mauro, you sent a patch to fix an spectre v1 issue in this file yesterday: dvb_ca_en50221.c:1480, but it seems there is another instance of the same issue some lines above:

drivers/media/dvb-core/dvb_ca_en50221.c +1 -0

index 1310526..7edd9db 100644
@@ -1398,6 +1398,7 @@ static int dvb_ca_en50221_io_do_ioctl(struct file 
 *file,
 
                 info->type = CA_CI_LINK;
                 info->flags = 0;
+               slot = array_index_nospec(slot, ca->slot_count + 1);
                 sl = &ca->slot_info[slot];
                 if ((sl->slot_state != DVB_CA_SLOTSTATE_NONE) &&

Quoted 3 lines

(sl->slot_state != DVB_CA_SLOTSTATE_INVALID)) {

Hi Mauro,

Just to let you know, I was running smatch during the weekend and the tool is still reporting all these Spectre media warnings (and a lot more):

https://patchwork.linuxtv.org/project/linux-media/list/?submitter=7277

Thanks
--
Gustavo

Dan Carpenter

2018-04-24 09:35 UTC #23 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

In reply to Mauro Carvalho Chehab

Hi Mauro,

I saw your comment on LWN. You argue on LWN that since the format array is static the CPU won't speculatively read past the L1 cache?

I don't know if that's true. It should be easy enough to filter out the reads into static arrays. Peter do you know the answer here?

regards,
dan carpenter

Quoted 95 lines · Mauro Carvalho Chehab

Em Mon, 23 Apr 2018 12:38:03 -0500
"Gustavo A. R. Silva" <[email protected]> escreveu:
Quoted 35 lines
f->index can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.
Smatch warning:
drivers/media/usb/tm6000/tm6000-video.c:879 vidioc_enum_fmt_vid_cap() warn: potential spectre issue 'format'
Fix this by sanitizing f->index before using it to index array _format_
Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1].
[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
Cc [email protected]
Reported-by Dan Carpenter <[email protected]>
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
 drivers/media/usb/tm6000/tm6000-video.c | 2 ++
 1 file changed, 2 insertions(+)
drivers/media/usb/tm6000/tm6000-video.c +1 -0
index b2399d4..d701027 100644
@@ -26,6 +26,7 @@
 #include <linux/kthread.h>
 #include <linux/highmem.h>
 #include <linux/freezer.h>
+#include <linux/nospec.h>
 
 #include "tm6000-regs.h"
 #include "tm6000.h"
drivers/media/usb/tm6000/tm6000-video.c static int vidioc_enum_fmt_vid_cap(struct file *file, void *priv, · line 879
Quoted 4 lines
drivers/media/usb/tm6000/tm6000-video.c +1 -0
@@ -875,6 +876,7 @@ static int vidioc_enum_fmt_vid_cap(struct file *file, void  *priv,
 	if (f->index >= ARRAY_SIZE(format))
 		return -EINVAL;
 
+	f->index = array_index_nospec(f->index, ARRAY_SIZE(format));
Please enlighten me: how do you think this could be exploited?
When an application calls VIDIOC_ENUM_FMT from a /dev/video0 device, it will just enumerate a hardware functionality, with is constant for a given hardware piece.
The way it works is that userspace do something like:
	int ret = 0;

	for (i = 0; ret == 0; i++) {
		ret = ioctl(VIDIOC_ENUM_FMT, ...);
	}
in order to read an entire const table.
Usually, it doesn't require any special privilege to call this ioctl, but, even if someone changes its permission to 0x400, a simple lsusb output is enough to know what hardware model is there. A lsmod or cat /proc/modules) also tells that the tm6000 module was loaded, with is a very good hint that the tm6000 is there or was there in the past.
In the specific case of tm6000, all hardware supports exactly the same formats, as this is usually defined per-driver. So, a quick look at the driver is enough to know exactly what the ioctl would answer. Also, the net is full of other resources that would allow anyone to get the supported formats for a piece of hardware.
Even assuming that the OS doesn't have lsusb, that /proc is not mounted, that /dev/video0 require special permissions, that the potential attacker doesn't have physical access to the equipment (in order to see if an USB board is plugged), etc... What possible harm he could do by identifying a hardware feature?
Similar notes for the other patches to drivers/media in this
series: let's not just start adding bloatware where not needed.
Please notice that I'm fine if you want to submit potential Spectre variant 1 fixups, but if you're willing to do so, please provide an explanation about the potential threat scenarios that you're identifying at the code.
Dan,
It probably makes sense to have somewhere at smatch a place where we could explicitly mark the false-positives, in order to avoid use to receive patches that would just add an extra delay where it is not needed.
Regards,
Mauro

Mauro Carvalho Chehab

maintainer

2018-04-24 10:11 UTC #24 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Hi Dan,

Em Tue, 24 Apr 2018 12:35:00 +0300
Dan Carpenter <[email protected]> escreveu:

Quoted 4 lines

Hi Mauro,
I saw your comment on LWN. You argue on LWN that since the format array is static the CPU won't speculatively read past the L1 cache?

The intent of that comment is to be provocative, in the sense that people would argue against and point flaws (if any) on my rationale.

As I explained when reviewing this patch, I don't care much if an automatic tool is saying that there's a vulnerability at the code, as it could be a false positive. So, what I want at the patch description is a threat analysis explaining how an algorithm is exploited.

With regards to Spectre, I never tried to write an exploit myself, nor had to study it in detail in order to mitigate it. So, what I know about it is what I read on a few places. From the places where I read, the boundaries for an array exploit are limited to L1 cache, but, as I said before, I can be wrong on that.

It will be great to hear to Peter's comment on that, as he knows a lot more than me about it.

Quoted 104 lines

I don't know if that's true. It should be easy enough to filter out the reads into static arrays. Peter do you know the answer here?
regards,
dan carpenter
Quoted 95 lines · Mauro Carvalho Chehab
Em Mon, 23 Apr 2018 12:38:03 -0500
"Gustavo A. R. Silva" <[email protected]> escreveu:
Quoted 35 lines
f->index can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.
Smatch warning:
drivers/media/usb/tm6000/tm6000-video.c:879 vidioc_enum_fmt_vid_cap() warn: potential spectre issue 'format'
Fix this by sanitizing f->index before using it to index array _format_
Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1].
[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
Cc [email protected]
Reported-by Dan Carpenter <[email protected]>
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
 drivers/media/usb/tm6000/tm6000-video.c | 2 ++
 1 file changed, 2 insertions(+)
drivers/media/usb/tm6000/tm6000-video.c +1 -0
index b2399d4..d701027 100644
@@ -26,6 +26,7 @@
 #include <linux/kthread.h>
 #include <linux/highmem.h>
 #include <linux/freezer.h>
+#include <linux/nospec.h>
 
 #include "tm6000-regs.h"
 #include "tm6000.h"
drivers/media/usb/tm6000/tm6000-video.c static int vidioc_enum_fmt_vid_cap(struct file *file, void *priv, · line 879
Quoted 4 lines
drivers/media/usb/tm6000/tm6000-video.c +1 -0
@@ -875,6 +876,7 @@ static int vidioc_enum_fmt_vid_cap(struct file *file, void  *priv,
 	if (f->index >= ARRAY_SIZE(format))
 		return -EINVAL;
 
+	f->index = array_index_nospec(f->index, ARRAY_SIZE(format));  
Please enlighten me: how do you think this could be exploited?
When an application calls VIDIOC_ENUM_FMT from a /dev/video0 device, it will just enumerate a hardware functionality, with is constant for a given hardware piece.
The way it works is that userspace do something like:
	int ret = 0;

	for (i = 0; ret == 0; i++) {
		ret = ioctl(VIDIOC_ENUM_FMT, ...);
	}
in order to read an entire const table.
Usually, it doesn't require any special privilege to call this ioctl, but, even if someone changes its permission to 0x400, a simple lsusb output is enough to know what hardware model is there. A lsmod or cat /proc/modules) also tells that the tm6000 module was loaded, with is a very good hint that the tm6000 is there or was there in the past.
In the specific case of tm6000, all hardware supports exactly the same formats, as this is usually defined per-driver. So, a quick look at the driver is enough to know exactly what the ioctl would answer. Also, the net is full of other resources that would allow anyone to get the supported formats for a piece of hardware.
Even assuming that the OS doesn't have lsusb, that /proc is not mounted, that /dev/video0 require special permissions, that the potential attacker doesn't have physical access to the equipment (in order to see if an USB board is plugged), etc... What possible harm he could do by identifying a hardware feature?
Similar notes for the other patches to drivers/media in this
series: let's not just start adding bloatware where not needed.
Please notice that I'm fine if you want to submit potential Spectre variant 1 fixups, but if you're willing to do so, please provide an explanation about the potential threat scenarios that you're identifying at the code.
Dan,
It probably makes sense to have somewhere at smatch a place where we could explicitly mark the false-positives, in order to avoid use to receive patches that would just add an extra delay where it is not needed.
Regards,
Mauro

Thanks,
Mauro

Peter Zijlstra

2018-04-24 10:36 UTC #25 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

In reply to Dan Carpenter

Quoted 11 lines · Dan Carpenter

Quoted 10 lines · Mauro Carvalho Chehab
Em Mon, 23 Apr 2018 12:38:03 -0500
"Gustavo A. R. Silva" <[email protected]> escreveu:
drivers/media/usb/tm6000/tm6000-video.c static int vidioc_enum_fmt_vid_cap(struct file *file, void *priv, · line 879
Quoted 5 lines
drivers/media/usb/tm6000/tm6000-video.c +1 -0
@@ -875,6 +876,7 @@ static int vidioc_enum_fmt_vid_cap(struct file *file, void  *priv,
 	if (f->index >= ARRAY_SIZE(format))
 		return -EINVAL;
 
+	f->index = array_index_nospec(f->index, ARRAY_SIZE(format));
Please enlighten me: how do you think this could be exploited?

TL;DR: read the papers [1] & [2]

I suspect you didn't get the gist of Spectre V1 [1], let me explain:

Suppose userspace provides f->index > ARRAY_SIZE(format), and we predict the branch to -EINVAL to not be taken.

Then the CPU _WILL_ load (out of bounds) format[f->index] into f->pixelformat and continue onwards to use this bogus value, all the way until it figures out the branch was mis-predicted.

Once it figures out the mispredict, it will throw away the state and start over at the condition site. So far, so basic.

The thing is, is will not (and cannot) throw away all state. Suppose our speculation continues into v4l_fill_fmtdesc() and that switch there is compiled as another array lookup, it will then feed our f->pixelformat (which contains random kernel memory) into that array to find the requested descr pointer.

Now, imagine userspace having flushed cache on the descr pointer array, having trained the branch predictor to mis-predict the branch (see branchscope paper [2]) and doing that out-of-bounds ioctl().

It can then speculative do the out-of-bounds array access, followed by the desc array load, then figure out it was wrong and redo.

Then usespace probes which part of the descr[] array is now in cache and from that it can infer the initial out-of-bound value.

So while format[] is static and bound, it can read random kernel memory up to format+4g, including your crypto keys.

As far as V1 goes, this is actually a fairly solid exploit candidate. No false positive about it.

Now kernel policy is to kill any and all speculation on user controlled array indexing such that we don't have to go look for subsequent side channels (the above cache side channel is the one described in the Spectre paper and by far the easiest, but there are other possible side channels) and we simply don't want to worry about it.

So even from that pov, the proposed patch is good.

[1] https://spectreattack.com/spectre.pdf
[2] www.cs.ucr.edu/~nael/pubs/asplos18.pdf

Peter Zijlstra

2018-04-24 11:21 UTC #26 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Quoted 3 lines · Peter Zijlstra

Then usespace probes which part of the descr[] array is now in cache and from that it can infer the initial out-of-bound value.

Just had a better look at v4l_fill_fmtdesc() and actually read the comment. The code cannot be compiled as a array because it is big and sparse. But the log(n) condition tree is a prime candidate for the branchscope side-channel, which would be able to reconstruct a significant number of bits of the original value. A denser tree gives more bits etc.

Mauro Carvalho Chehab

maintainer

2018-04-24 17:48 UTC #27 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

In reply to Peter Zijlstra

Em Tue, 24 Apr 2018 12:36:09 +0200
Peter Zijlstra <[email protected]> escreveu:

Quoted 66 lines · Dan Carpenter

Quoted 11 lines · Mauro Carvalho Chehab
Quoted 10 lines
Em Mon, 23 Apr 2018 12:38:03 -0500
"Gustavo A. R. Silva" <[email protected]> escreveu:
drivers/media/usb/tm6000/tm6000-video.c static int vidioc_enum_fmt_vid_cap(struct file *file, void *priv, · line 879
Quoted 5 lines
drivers/media/usb/tm6000/tm6000-video.c +1 -0
@@ -875,6 +876,7 @@ static int vidioc_enum_fmt_vid_cap(struct file *file, void  *priv,
 	if (f->index >= ARRAY_SIZE(format))
 		return -EINVAL;
 
+	f->index = array_index_nospec(f->index, ARRAY_SIZE(format));  
Please enlighten me: how do you think this could be exploited?
TL;DR: read the papers [1] & [2]
I suspect you didn't get the gist of Spectre V1 [1], let me explain:
Suppose userspace provides f->index > ARRAY_SIZE(format), and we predict the branch to -EINVAL to not be taken.
Then the CPU _WILL_ load (out of bounds) format[f->index] into f->pixelformat and continue onwards to use this bogus value, all the way until it figures out the branch was mis-predicted.
Once it figures out the mispredict, it will throw away the state and start over at the condition site. So far, so basic.
The thing is, is will not (and cannot) throw away all state. Suppose our speculation continues into v4l_fill_fmtdesc() and that switch there is compiled as another array lookup, it will then feed our f->pixelformat (which contains random kernel memory) into that array to find the requested descr pointer.
Now, imagine userspace having flushed cache on the descr pointer array, having trained the branch predictor to mis-predict the branch (see branchscope paper [2]) and doing that out-of-bounds ioctl().
It can then speculative do the out-of-bounds array access, followed by the desc array load, then figure out it was wrong and redo.
Then usespace probes which part of the descr[] array is now in cache and from that it can infer the initial out-of-bound value.
So while format[] is static and bound, it can read random kernel memory up to format+4g, including your crypto keys.
As far as V1 goes, this is actually a fairly solid exploit candidate. No false positive about it.
Now kernel policy is to kill any and all speculation on user controlled array indexing such that we don't have to go look for subsequent side channels (the above cache side channel is the one described in the Spectre paper and by far the easiest, but there are other possible side channels) and we simply don't want to worry about it.
So even from that pov, the proposed patch is good.
[1] https://spectreattack.com/spectre.pdf
[2] www.cs.ucr.edu/~nael/pubs/asplos18.pdf
Quoted 3 lines · Peter Zijlstra
Then usespace probes which part of the descr[] array is now in cache and from that it can infer the initial out-of-bound value.

Quoted 6 lines

Just had a better look at v4l_fill_fmtdesc() and actually read the comment. The code cannot be compiled as a array because it is big and sparse. But the log(n) condition tree is a prime candidate for the branchscope side-channel, which would be able to reconstruct a significant number of bits of the original value. A denser tree gives more bits etc.

Peter,

Thanks for a comprehensive explanation about that. It now makes more sense to me.

Yeah, better to apply a fix to avoid the issue with VIDIOC_ENUM_FMT.

Btw, on almost all media drivers, the implementation for enumerating the supported formats are the same (and we have a few other VIDOC_ENUM_foo ioctls that usually do similar stuff): the V4L2 core calls a driver, with looks into an array, returning the results to the core.

So, a fix like that should likely go to almost all media drivers (there are a lot of them!), and, for every new one, to take care to avoid introducing it again during patch review process.

So, I'm wondering if are there any way to mitigate it inside the core itself, instead of doing it on every driver, e. g. changing v4l_enum_fmt() implementation at v4l2-ioctl.

Ok, a "poor man" approach would be to pass the array directly to the core and let the implementation there to implement the array fetch logic, calling array_index_nospec() there, but I wonder if are there any other way that won't require too much code churn.

Thanks,
Mauro

Peter Zijlstra

2018-04-24 18:48 UTC #28 lore raw

Re: [PATCH 01/11] media: tm6000: fix potential Spectre variant 1

Quoted 8 lines · Mauro Carvalho Chehab

So, I'm wondering if are there any way to mitigate it inside the core itself, instead of doing it on every driver, e. g. changing v4l_enum_fmt() implementation at v4l2-ioctl.
Ok, a "poor man" approach would be to pass the array directly to the core and let the implementation there to implement the array fetch logic, calling array_index_nospec() there, but I wonder if are there any other way that won't require too much code churn.

Sadly no; the whole crux is the array bound check itself. You could maybe pass around the array size to the core code and then do something like:

	if (f->index >= f->array_size)
		return -EINVAL;

	f->index = nospec_array_index(f->index, f->array_size);

in generic code, and have all the drivers use f->index as usual, but even that would be quite a bit of code churn I guess.

Gustavo A. R. Silva

author

2018-04-23 17:38 UTC #29 lore raw

PATCH 2/11 exynos4-is: mipi-csis: fix potential Spectre variant 1

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

code->index can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.

Smatch warning:
drivers/media/platform/exynos4-is/mipi-csis.c:549 s5pcsis_enum_mbus_code() warn: potential spectre issue 's5pcsis_formats'

Fix this by sanitizing code->index before using it to index s5pcsis_formats.

Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1].

Cc stable at vger.kernel.org

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
 drivers/media/platform/exynos4-is/mipi-csis.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

drivers/media/platform/exynos4-is/mipi-csis.c +4 -1

index cba46a6..60104c1 100644
@@ -35,6 +35,8 @@
 
 #include "mipi-csis.h"
 
+#include <linux/nospec.h>
+
 static int debug;
 module_param(debug, int, 0644);
 MODULE_PARM_DESC(debug, "Debug level (0-2)");

@@ -545,7 +547,8 @@ static int s5pcsis_enum_mbus_code(struct v4l2_subdev *sd,
 {
 	if (code->index >= ARRAY_SIZE(s5pcsis_formats))
 		return -EINVAL;
-
+	code->index = array_index_nospec(code->index,
+					 ARRAY_SIZE(s5pcsis_formats));
 	code->code = s5pcsis_formats[code->index].code;
 	return 0;
 }

Signature · 1 line

2.7.4

Gustavo A. R. Silva

author

2018-04-23 17:39 UTC #30 lore raw

PATCH 3/11 fsl-viu: fix potential Spectre variant 1

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

f->index can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.

Smatch warning:
drivers/media/platform/fsl-viu.c:587 vidioc_enum_fmt() warn: potential spectre issue 'formats'

Fix this by sanitizing f->index before using it to index formats.

Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1].

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
 drivers/media/platform/fsl-viu.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

drivers/media/platform/fsl-viu.c +4 -4

index e41510c..8356d26 100644
@@ -33,6 +33,8 @@
 #include <media/v4l2-event.h>
 #include <media/videobuf-dma-contig.h>
 
+#include <linux/nospec.h>
+
 #define DRV_NAME		"fsl_viu"
 #define VIU_VERSION		"0.5.1"

@@ -579,12 +581,10 @@ static int vidioc_querycap(struct file *file, void *priv,
 static int vidioc_enum_fmt(struct file *file, void  *priv,
 					struct v4l2_fmtdesc *f)
 {
-	int index = f->index;
-
 	if (f->index >= NUM_FORMATS)
 		return -EINVAL;
-
-	f->pixelformat = formats[index].fourcc;
+	f->index = array_index_nospec(f->index, NUM_FORMATS);
+	f->pixelformat = formats[f->index].fourcc;
 	return 0;
 }

Signature · 1 line

2.7.4

Gustavo A. R. Silva

author

2018-04-23 17:41 UTC #31 lore raw

PATCH 4/11 marvell-ccic: mcam-core: fix potential Spectre variant 1

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

fmt->index can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.

Smatch warning:
drivers/media/platform/marvell-ccic/mcam-core.c:1323 mcam_vidioc_enum_fmt_vid_cap() warn: potential spectre issue 'mcam_formats'

Fix this by sanitizing fmt->index before using it to index mcam_formats.

Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1].

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
 drivers/media/platform/marvell-ccic/mcam-core.c | 3 +++
 1 file changed, 3 insertions(+)

drivers/media/platform/marvell-ccic/mcam-core.c +3 -0

index 80670ee..0a54dba 100644
@@ -33,6 +33,8 @@
 
 #include "mcam-core.h"
 
+#include <linux/nospec.h>
+
 #ifdef MCAM_MODE_VMALLOC
 /*
  * Internal DMA buffer management.  Since the controller cannot do S/G I/O,

@@ -1318,6 +1320,7 @@ static int mcam_vidioc_enum_fmt_vid_cap(struct file *filp,
 {
 	if (fmt->index >= N_MCAM_FMTS)
 		return -EINVAL;
+	fmt->index = array_index_nospec(fmt->index, N_MCAM_FMTS);
 	strlcpy(fmt->description, mcam_formats[fmt->index].desc,
 			sizeof(fmt->description));
 	fmt->pixelformat = mcam_formats[fmt->index].pixelformat;

Signature · 1 line

2.7.4

Gustavo A. R. Silva

author

2018-04-23 17:42 UTC #32 lore raw

PATCH 5/11 omap_vout: fix potential Spectre variant 1

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

index can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.

Smatch warning:
drivers/media/platform/omap/omap_vout.c:1062 vidioc_enum_fmt_vid_out() warn: potential spectre issue 'omap_formats'

Fix this by sanitizing index before using it to index omap_formats.

Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1].

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
 drivers/media/platform/omap/omap_vout.c | 3 +++
 1 file changed, 3 insertions(+)

drivers/media/platform/omap/omap_vout.c +3 -0

index 5700b78..1a7ec39 100644
@@ -51,6 +51,8 @@
 #include "omap_voutdef.h"
 #include "omap_vout_vrfb.h"
 
+#include <linux/nospec.h>
+
 MODULE_AUTHOR("Texas Instruments");
 MODULE_DESCRIPTION("OMAP Video for Linux Video out driver");
 MODULE_LICENSE("GPL");

@@ -1059,6 +1061,7 @@ static int vidioc_enum_fmt_vid_out(struct file *file, void *fh,
 	if (index >= NUM_OUTPUT_FORMATS)
 		return -EINVAL;
 
+	index = array_index_nospec(index, NUM_OUTPUT_FORMATS);
 	fmt->flags = omap_formats[index].flags;
 	strlcpy(fmt->description, omap_formats[index].description,
 			sizeof(fmt->description));

Signature · 1 line

2.7.4

Gustavo A. R. Silva

author

2018-04-23 17:47 UTC #33 lore raw

PATCH 6/11 rcar-v4l2: fix potential Spectre variant 1

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

f->index can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.

Smatch warning:
drivers/media/platform/rcar-vin/rcar-v4l2.c:344 rvin_enum_fmt_vid_cap() warn: potential spectre issue 'rvin_formats'

Fix this by sanitizing f->index before using it to index rvin_formats.

Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1].

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
 drivers/media/platform/rcar-vin/rcar-v4l2.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

drivers/media/platform/rcar-vin/rcar-v4l2.c +3 -1

index b479b88..bbfc3b8 100644
@@ -22,6 +22,8 @@
 
 #include "rcar-vin.h"
 
+#include <linux/nospec.h>
+
 #define RVIN_DEFAULT_FORMAT	V4L2_PIX_FMT_YUYV
 #define RVIN_MAX_WIDTH		2048
 #define RVIN_MAX_HEIGHT		2048

@@ -340,7 +342,7 @@ static int rvin_enum_fmt_vid_cap(struct file *file, void *priv,
 {
 	if (f->index >= ARRAY_SIZE(rvin_formats))
 		return -EINVAL;
-
+	f->index = array_index_nospec(f->index, ARRAY_SIZE(rvin_formats));
 	f->pixelformat = rvin_formats[f->index].fourcc;
 
 	return 0;

Signature · 1 line

2.7.4

Gustavo A. R. Silva

author

2018-04-23 17:48 UTC #34 lore raw

PATCH 7/11 rcar_drif: fix potential Spectre variant 1

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

f->index can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.

Smatch warning:
drivers/media/platform/rcar_drif.c:909 rcar_drif_enum_fmt_sdr_cap() warn: potential spectre issue 'formats'

Fix this by sanitizing f->index before using it to index formats.

Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1].

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
 drivers/media/platform/rcar_drif.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

drivers/media/platform/rcar_drif.c +3 -1

index dc7e280..2c21ec2 100644
@@ -66,6 +66,8 @@
 #include <media/videobuf2-v4l2.h>
 #include <media/videobuf2-vmalloc.h>
 
+#include <linux/nospec.h>
+
 /* DRIF register offsets */
 #define RCAR_DRIF_SITMDR1			0x00
 #define RCAR_DRIF_SITMDR2			0x04

@@ -905,7 +907,7 @@ static int rcar_drif_enum_fmt_sdr_cap(struct file *file, void *priv,
 {
 	if (f->index >= ARRAY_SIZE(formats))
 		return -EINVAL;
-
+	f->index = array_index_nospec(f->index, ARRAY_SIZE(formats));
 	f->pixelformat = formats[f->index].pixelformat;
 
 	return 0;

Signature · 1 line

2.7.4

Gustavo A. R. Silva

author

2018-04-23 17:49 UTC #35 lore raw

PATCH 8/11 sh_vou: fix potential Spectre variant 1

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

fmt->index can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.

Smatch warning:
drivers/media/platform/sh_vou.c:407 sh_vou_enum_fmt_vid_out() warn: potential spectre issue 'vou_fmt'

Fix this by sanitizing fmt->index before using it to index vou_fmt.

Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1].

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
 drivers/media/platform/sh_vou.c | 3 +++
 1 file changed, 3 insertions(+)

drivers/media/platform/sh_vou.c +3 -0

index 4dccf29..58d8645 100644
@@ -30,6 +30,8 @@
 #include <media/videobuf2-v4l2.h>
 #include <media/videobuf2-dma-contig.h>
 
+#include <linux/nospec.h>
+
 /* Mirror addresses are not available for all registers */
 #define VOUER	0
 #define VOUCR	4

@@ -398,6 +400,7 @@ static int sh_vou_enum_fmt_vid_out(struct file *file, void  *priv,
 
 	if (fmt->index >= ARRAY_SIZE(vou_fmt))
 		return -EINVAL;
+	fmt->index = array_index_nospec(fmt->index, ARRAY_SIZE(vou_fmt));
 
 	dev_dbg(vou_dev->v4l2_dev.dev, "%s()\n", __func__);

Signature · 1 line

2.7.4

Gustavo A. R. Silva

author

2018-04-23 17:50 UTC #36 lore raw

PATCH 9/11 vimc-debayer: fix potential Spectre variant 1

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

code->index can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.

Smatch warning:
drivers/media/platform/vimc/vimc-debayer.c:182 vimc_deb_enum_mbus_code() warn: potential spectre issue 'vimc_deb_pix_map_list'

Fix this by sanitizing code->index before using it to index vimc_deb_pix_map_list.

Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1].

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
 drivers/media/platform/vimc/vimc-debayer.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

drivers/media/platform/vimc/vimc-debayer.c +4 -1

index 6e10b63..bdd96bb 100644
@@ -24,6 +24,8 @@
 
 #include "vimc-common.h"
 
+#include <linux/nospec.h>
+
 #define VIMC_DEB_DRV_NAME "vimc-debayer"
 
 static unsigned int deb_mean_win_size = 3;

@@ -178,7 +180,8 @@ static int vimc_deb_enum_mbus_code(struct v4l2_subdev *sd,
 	} else {
 		if (code->index >= ARRAY_SIZE(vimc_deb_pix_map_list))
 			return -EINVAL;
-
+		code->index = array_index_nospec(code->index,
+					    ARRAY_SIZE(vimc_deb_pix_map_list));
 		code->code = vimc_deb_pix_map_list[code->index].code;
 	}

Signature · 1 line

2.7.4

Gustavo A. R. Silva

author

2018-04-23 17:51 UTC #37 lore raw

PATCH 10/11 vivid-sdr-cap: fix potential Spectre variant 1

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

band->index can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.

Smatch warning:
drivers/media/platform/vivid/vivid-sdr-cap.c:323 vivid_sdr_enum_freq_bands() warn: potential spectre issue 'bands_adc'

Fix this by sanitizing band->index before using it to index bands_adc and bands_fm.

Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1].

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
 drivers/media/platform/vivid/vivid-sdr-cap.c | 6 ++++++
 1 file changed, 6 insertions(+)

drivers/media/platform/vivid/vivid-sdr-cap.c +6 -0

index cfb7cb4..684d8a2 100644
@@ -22,6 +22,8 @@
 #include "vivid-ctrls.h"
 #include "vivid-sdr-cap.h"
 
+#include <linux/nospec.h>
+
 /* stream formats */
 struct vivid_format {
 	u32	pixelformat;

@@ -320,11 +322,15 @@ int vivid_sdr_enum_freq_bands(struct file *file, void *fh,
 	case 0:
 		if (band->index >= ARRAY_SIZE(bands_adc))
 			return -EINVAL;
+		band->index = array_index_nospec(band->index,
+						 ARRAY_SIZE(bands_adc));
 		*band = bands_adc[band->index];
 		return 0;
 	case 1:
 		if (band->index >= ARRAY_SIZE(bands_fm))
 			return -EINVAL;
+		band->index = array_index_nospec(band->index,
+						 ARRAY_SIZE(bands_fm));
 		*band = bands_fm[band->index];
 		return 0;
 	default:

Signature · 1 line

2.7.4

Gustavo A. R. Silva

author

2018-04-23 17:52 UTC #38 lore raw

PATCH 11/11 vsp1_rwpf: fix potential Spectre variant 1

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

code->index can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.

Smatch warning:
drivers/media/platform/vsp1/vsp1_rwpf.c:47 vsp1_rwpf_enum_mbus_code() warn: potential spectre issue 'codes'

Fix this by sanitizing code->index before using it to index codes.

Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1].

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
 drivers/media/platform/vsp1/vsp1_rwpf.c | 3 +++
 1 file changed, 3 insertions(+)

drivers/media/platform/vsp1/vsp1_rwpf.c +3 -0

index cfd8f19..6e887be 100644
@@ -13,6 +13,8 @@
 
 #include <media/v4l2-subdev.h>
 
+#include <linux/nospec.h>
+
 #include "vsp1.h"
 #include "vsp1_rwpf.h"
 #include "vsp1_video.h"

@@ -44,6 +46,7 @@ static int vsp1_rwpf_enum_mbus_code(struct v4l2_subdev *subdev,
 	if (code->index >= ARRAY_SIZE(codes))
 		return -EINVAL;
 
+	code->index = array_index_nospec(code->index, ARRAY_SIZE(codes));
 	code->code = codes[code->index];
 
 	return 0;

Signature · 1 line

2.7.4

Gustavo A. R. Silva

author

2018-04-23 19:13 UTC #39 lore raw