Remove VLA usage in rtc-s5m

PATCH In review Gustavo A. R. Silva 4 participants 9 messages Mar 10, 2018 – Mar 13, 2018

Subsystems (4)

Arm Samsung Exynos Multifunction devices (MFD) Real time clock (RTC) Samsung multifunction PMIC device drivers

lore

Share & tools

lore

Gustavo A. R. Silva

author

2018-03-10 06:27 UTC #0 lore raw

cover Remove VLA usage in rtc-s5m

This patchset aims to remove VLA usage from rtc-s5m.

The first patch moves an enum from rtc.h to rtc-s5m.c, as this is the only driver in which such enum is actually being used [1].

The second patch adds the enum name RTC_MAX_NUM_TIME_REGS, which will be used as a maximum length to the current VLAs, hence turning them into fixed-length arrays instead.

[1] https://marc.info/?l=linux-rtc&m=152060068925948&w=2

Thanks

Gustavo A. R. Silva (2):
rtc: s5m: move enum from rtc.h to rtc-s5m.c
rtc: s5m: Remove VLA usage

 drivers/rtc/rtc-s5m.c           | 25 +++++++++++++++++++------
 include/linux/mfd/samsung/rtc.h | 11 -----------
 2 files changed, 19 insertions(+), 17 deletions(-)

Signature · 1 line

2.7.4

Gustavo A. R. Silva

author

2018-03-10 06:27 UTC #1 lore raw

PATCH 1/2 rtc: s5m: Move enum from rtc.h to rtc-s5m.c

Move this enum to rtc-s5m.c once it is meaningless to others drivers [1].

[1] https://marc.info/?l=linux-rtc&m=152060068925948&w=2

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

---
 drivers/rtc/rtc-s5m.c           | 11 +++++++++++
 include/linux/mfd/samsung/rtc.h | 11 -----------
 2 files changed, 11 insertions(+), 11 deletions(-)

drivers/rtc/rtc-s5m.c +11 -0

index 6deae10..4c363de 100644
@@ -38,6 +38,17 @@
  */
 #define UDR_READ_RETRY_CNT	5
 
+enum {
+	RTC_SEC = 0,
+	RTC_MIN,
+	RTC_HOUR,
+	RTC_WEEKDAY,
+	RTC_DATE,
+	RTC_MONTH,
+	RTC_YEAR1,
+	RTC_YEAR2,
+};
+
 /*
  * Registers used by the driver which are different between chipsets.
  *

include/linux/mfd/samsung/rtc.h +0 ~~-11~~

index 48c3c5b..9ed2871 100644
@@ -141,15 +141,4 @@ enum s2mps_rtc_reg {
 #define WTSR_ENABLE_SHIFT	6
 #define WTSR_ENABLE_MASK	(1 << WTSR_ENABLE_SHIFT)
 
-enum {
-	RTC_SEC = 0,
-	RTC_MIN,
-	RTC_HOUR,
-	RTC_WEEKDAY,
-	RTC_DATE,
-	RTC_MONTH,
-	RTC_YEAR1,
-	RTC_YEAR2,
-};
-
 #endif /*  __LINUX_MFD_SEC_RTC_H */

Signature · 1 line

2.7.4

Krzysztof Kozlowski

maintainer Reviewed-by on v1 1/2

2018-03-11 16:39 UTC #2 lore raw

Re: [PATCH 1/2] rtc: s5m: Move enum from rtc.h to rtc-s5m.c

Quoted 3 lines · Gustavo A. R. Silva

Move this enum to rtc-s5m.c once it is meaningless to others drivers [1].
[1] https://marc.info/?l=linux-rtc&m=152060068925948&w=2

Instead of external link (which might or might not work soon) you can just put "Suggested-by: Krzysztof Kozlowski <[email protected]>".

Anyway:

Reviewed-by Krzysztof Kozlowski <[email protected]>

Best regards,
Krzysztof

Gustavo A. R. Silva

author

2018-03-13 03:22 UTC #3 lore raw

Re: [PATCH 1/2] rtc: s5m: Move enum from rtc.h to rtc-s5m.c

Quoted 9 lines · Krzysztof Kozlowski

Quoted 3 lines · Gustavo A. R. Silva
Move this enum to rtc-s5m.c once it is meaningless to others drivers [1].
[1] https://marc.info/?l=linux-rtc&m=152060068925948&w=2
Instead of external link (which might or might not work soon) you can just put "Suggested-by: Krzysztof Kozlowski <[email protected]>".

I got it.
I'll do that next time.

Quoted 3 lines

Anyway:
Reviewed-by Krzysztof Kozlowski <[email protected]>

Thanks for reviewing it.
--
Gustavo

Lee Jones

Acked-by on v1 1/2

2018-03-12 08:54 UTC #4 lore raw

Re: [PATCH 1/2] rtc: s5m: Move enum from rtc.h to rtc-s5m.c

In reply to Gustavo A. R. Silva

Quoted 8 lines · Gustavo A. R. Silva

Move this enum to rtc-s5m.c once it is meaningless to others drivers [1].
[1] https://marc.info/?l=linux-rtc&m=152060068925948&w=2
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
 drivers/rtc/rtc-s5m.c           | 11 +++++++++++
 include/linux/mfd/samsung/rtc.h | 11 -----------

I don't think this will conflict with anything (unless some major works are carried out within the next few weeks - in which case I'll need a pull-request, but for now ...)

Acked-by Lee Jones <[email protected]>

Signature · 4 lines

Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

Gustavo A. R. Silva

author

2018-03-10 06:27 UTC #5 lore raw

PATCH 2/2 rtc: s5m: Remove VLA usage

In reply to Gustavo A. R. Silva

In preparation to enabling -Wvla, remove VLAs and replace them with fixed-length arrays instead.

Quoted 1 line

From a security viewpoint, the use of Variable Length Arrays can be

a vector for stack overflow attacks. Also, in general, as the code evolves it is easy to lose track of how big a VLA can get. Thus, we can end up having segfaults that are hard to debug.

Also, fixed as part of the directive to remove all VLAs from the kernel: https://lkml.org/lkml/2018/3/7/621

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

---
 drivers/rtc/rtc-s5m.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

drivers/rtc/rtc-s5m.c +8 -6

index 4c363de..8428455 100644
@@ -47,6 +47,8 @@ enum {
 	RTC_MONTH,
 	RTC_YEAR1,
 	RTC_YEAR2,
+	/* Make sure this is always the last enum name. */
+	RTC_MAX_NUM_TIME_REGS
 };
 
 /*

@@ -378,7 +380,7 @@ static void s5m8763_tm_to_data(struct rtc_time *tm, u8 *data)
 static int s5m_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct s5m_rtc_info *info = dev_get_drvdata(dev);
-	u8 data[info->regs->regs_count];
+	u8 data[RTC_MAX_NUM_TIME_REGS];
 	int ret;
 
 	if (info->regs->read_time_udr_mask) {

@@ -424,7 +426,7 @@ static int s5m_rtc_read_time(struct device *dev, struct rtc_time *tm)
 static int s5m_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct s5m_rtc_info *info = dev_get_drvdata(dev);
-	u8 data[info->regs->regs_count];
+	u8 data[RTC_MAX_NUM_TIME_REGS];
 	int ret = 0;
 
 	switch (info->device_type) {

@@ -461,7 +463,7 @@ static int s5m_rtc_set_time(struct device *dev, struct rtc_time *tm)
 static int s5m_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	struct s5m_rtc_info *info = dev_get_drvdata(dev);
-	u8 data[info->regs->regs_count];
+	u8 data[RTC_MAX_NUM_TIME_REGS];
 	unsigned int val;
 	int ret, i;

@@ -511,7 +513,7 @@ static int s5m_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 
 static int s5m_rtc_stop_alarm(struct s5m_rtc_info *info)
 {
-	u8 data[info->regs->regs_count];
+	u8 data[RTC_MAX_NUM_TIME_REGS];
 	int ret, i;
 	struct rtc_time tm;

@@ -556,7 +558,7 @@ static int s5m_rtc_stop_alarm(struct s5m_rtc_info *info)
 static int s5m_rtc_start_alarm(struct s5m_rtc_info *info)
 {
 	int ret;
-	u8 data[info->regs->regs_count];
+	u8 data[RTC_MAX_NUM_TIME_REGS];
 	u8 alarm0_conf;
 	struct rtc_time tm;

@@ -609,7 +611,7 @@ static int s5m_rtc_start_alarm(struct s5m_rtc_info *info)
 static int s5m_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
 	struct s5m_rtc_info *info = dev_get_drvdata(dev);
-	u8 data[info->regs->regs_count];
+	u8 data[RTC_MAX_NUM_TIME_REGS];
 	int ret;
 
 	switch (info->device_type) {

Signature · 1 line

2.7.4

Krzysztof Kozlowski

maintainer Reviewed-by on v1 2/2

2018-03-12 11:14 UTC #6 lore raw

Re: [PATCH 2/2] rtc: s5m: Remove VLA usage

Quoted 8 lines · Gustavo A. R. Silva

In preparation to enabling -Wvla, remove VLAs and replace them with fixed-length arrays instead.
From a security viewpoint, the use of Variable Length Arrays can be a vector for stack overflow attacks. Also, in general, as the code evolves it is easy to lose track of how big a VLA can get. Thus, we can end up having segfaults that are hard to debug.

Quoted 7 lines

Also, fixed as part of the directive to remove all VLAs from the kernel: https://lkml.org/lkml/2018/3/7/621
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
 drivers/rtc/rtc-s5m.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

Reviewed-by Krzysztof Kozlowski <[email protected]>

Best regards,
Krzysztof

Alexandre Belloni

maintainer

2018-03-13 00:35 UTC #7 lore raw

In reply to Gustavo A. R. Silva

Hi,

Quoted 9 lines · Gustavo A. R. Silva

This patchset aims to remove VLA usage from rtc-s5m.
The first patch moves an enum from rtc.h to rtc-s5m.c, as this is the only driver in which such enum is actually being used [1].
The second patch adds the enum name RTC_MAX_NUM_TIME_REGS, which will be used as a maximum length to the current VLAs, hence turning them into fixed-length arrays instead.

Quoted 8 lines

[1] https://marc.info/?l=linux-rtc&m=152060068925948&w=2
Thanks
Gustavo A. R. Silva (2):
rtc: s5m: move enum from rtc.h to rtc-s5m.c
rtc: s5m: Remove VLA usage

Both applied, thanks.

Signature · 3 lines

Alexandre Belloni, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

Gustavo A. R. Silva

author

2018-03-13 01:17 UTC #8 lore raw

Quoted 14 lines · Alexandre Belloni

Hi,
Quoted 11 lines · Gustavo A. R. Silva
This patchset aims to remove VLA usage from rtc-s5m.
The first patch moves an enum from rtc.h to rtc-s5m.c, as this is the only driver in which such enum is actually being used [1].
The second patch adds the enum name RTC_MAX_NUM_TIME_REGS, which will be used as a maximum length to the current VLAs, hence turning them into fixed-length arrays instead.
[1] https://marc.info/?l=linux-rtc&m=152060068925948&w=2

Quoted 9 lines

Quoted 6 lines
Thanks
Gustavo A. R. Silva (2):
rtc: s5m: move enum from rtc.h to rtc-s5m.c
rtc: s5m: Remove VLA usage
Both applied, thanks.

Awesome.

Thank you.
--
Gustavo