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comedi: misc fixes

PATCH Superseded Johan Hovold 2 participants 13 messages Oct 25, 2021 – Oct 27, 2021

Subsystems (3)
Stable branch USB Comedi drivers

v1 of 2 Superseded Latest is v2 →

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Johan Hovold

author
#0 lore raw

cover comedi: misc fixes

This series fixes a number of issues in the comedi drivers that were found through inspection.

Johan

Johan Hovold (5):
comedi: ni_usb6501: fix NULL-deref in command paths
comedi: dt9812: fix DMA buffers on stack
comedi: vmk80xx: fix transfer-buffer overflows
comedi: vmk80xx: fix bulk-buffer overflow
comedi: vmk80xx: fix bulk and interrupt message timeouts

 drivers/comedi/drivers/dt9812.c     | 109 +++++++++++++++++++++-------
 drivers/comedi/drivers/ni_usb6501.c |   8 ++
 drivers/comedi/drivers/vmk80xx.c    |  28 +++----
 3 files changed, 105 insertions(+), 40 deletions(-)
Signature · 1 line
2.32.0
author
#1 lore raw

PATCH 1/5 comedi: ni_usb6501: fix NULL-deref in command paths

The driver uses endpoint-sized USB transfer buffers but had no sanity checks on the sizes. This can lead to zero-size-pointer dereferences or overflowed transfer buffers in ni6501_port_command() and ni6501_counter_command() if a (malicious) device has smaller max-packet sizes than expected (or when doing descriptor fuzz testing).

Add the missing sanity checks to probe().

Fixes a03bb00e50ab ("staging: comedi: add NI USB-6501 support")
Cc [email protected] # 3.18
Cc Luca Ellero <[email protected]>
Signed-off-by Johan Hovold <[email protected]>
---
 drivers/comedi/drivers/ni_usb6501.c | 8 ++++++++
 1 file changed, 8 insertions(+)
drivers/comedi/drivers/ni_usb6501.c +8 -0
index 5b6d9d783b2f..eb2e5c23f25d 100644
@@ -144,6 +144,10 @@ static const u8 READ_COUNTER_RESPONSE[]	= {0x00, 0x01, 0x00, 0x10,
 					   0x00, 0x00, 0x00, 0x02,
 					   0x00, 0x00, 0x00, 0x00};
 
+/* Largest supported packets */
+static const size_t TX_MAX_SIZE	= sizeof(SET_PORT_DIR_REQUEST);
+static const size_t RX_MAX_SIZE	= sizeof(READ_PORT_RESPONSE);
+
 enum commands {
 	READ_PORT,
 	WRITE_PORT,

@@ -486,12 +490,16 @@ static int ni6501_find_endpoints(struct comedi_device *dev)
 		ep_desc = &iface_desc->endpoint[i].desc;
 
 		if (usb_endpoint_is_bulk_in(ep_desc)) {
+			if (usb_endpoint_maxp(ep_desc) < RX_MAX_SIZE)
+				continue;
 			if (!devpriv->ep_rx)
 				devpriv->ep_rx = ep_desc;
 			continue;
 		}
 
 		if (usb_endpoint_is_bulk_out(ep_desc)) {
+			if (usb_endpoint_maxp(ep_desc) < TX_MAX_SIZE)
+				continue;
 			if (!devpriv->ep_tx)
 				devpriv->ep_tx = ep_desc;
 			continue;
Signature · 1 line
2.32.0
maintainer
#2 lore raw

Re: [PATCH 1/5] comedi: ni_usb6501: fix NULL-deref in command paths

Quoted 39 lines · Johan Hovold

The driver uses endpoint-sized USB transfer buffers but had no sanity checks on the sizes. This can lead to zero-size-pointer dereferences or overflowed transfer buffers in ni6501_port_command() and ni6501_counter_command() if a (malicious) device has smaller max-packet sizes than expected (or when doing descriptor fuzz testing).

Add the missing sanity checks to probe().

Fixes a03bb00e50ab ("staging: comedi: add NI USB-6501 support")
Cc [email protected] # 3.18
Cc Luca Ellero <[email protected]>
Signed-off-by Johan Hovold <[email protected]>
---
  drivers/comedi/drivers/ni_usb6501.c | 8 ++++++++
  1 file changed, 8 insertions(+)
drivers/comedi/drivers/ni_usb6501.c +6 -0
index 5b6d9d783b2f..eb2e5c23f25d 100644
@@ -144,6 +144,10 @@ static const u8 READ_COUNTER_RESPONSE[]	= {0x00, 0x01, 0x00, 0x10,
  					   0x00, 0x00, 0x00, 0x02,
  					   0x00, 0x00, 0x00, 0x00};
 
+/* Largest supported packets */
+static const size_t TX_MAX_SIZE	= sizeof(SET_PORT_DIR_REQUEST);
+static const size_t RX_MAX_SIZE	= sizeof(READ_PORT_RESPONSE);
+
  enum commands {
  	READ_PORT,
  	WRITE_PORT,

@@ -486,12 +490,16 @@ static int ni6501_find_endpoints(struct comedi_device *dev)
  		ep_desc = &iface_desc->endpoint[i].desc;
 
  		if (usb_endpoint_is_bulk_in(ep_desc)) {
+			if (usb_endpoint_maxp(ep_desc) < RX_MAX_SIZE)
+				continue;
  			if (!devpriv->ep_rx)

drivers/comedi/drivers/ni_usb6501.c static int ni6501_find_endpoints(struct comedi_device *dev) · line 505

Quoted 10 lines
drivers/comedi/drivers/ni_usb6501.c +2 -0
  				devpriv->ep_rx = ep_desc;
  			continue;
  		}
 
  		if (usb_endpoint_is_bulk_out(ep_desc)) {
+			if (usb_endpoint_maxp(ep_desc) < TX_MAX_SIZE)
+				continue;
  			if (!devpriv->ep_tx)
  				devpriv->ep_tx = ep_desc;
  			continue;

Perhaps it should return an error if the first encountered bulk-in endpoint has the wrong size or the first encountered bulk-out endpoint has the wrong size. Something like:

		if (usb_endpoint_is_bulk_in(ep_desc)) {
			if (!devpriv->ep_rx) {
				if (usb_endpoint_maxp(ep_desc) < RX_MAX_SIZE)
					break;
			}
			continue;

(similar for bulk-out with TX_MAX_SIZE)

Signature · 4 lines
-=( Ian Abbott <[email protected]> || MEV Ltd. is a company  )=-
-=( registered in England & Wales.  Regd. number: 02862268.  )=-
-=( Regd. addr.: S11 & 12 Building 67, Europa Business Park, )=-
-=( Bird Hall Lane, STOCKPORT, SK3 0XA, UK. || www.mev.co.uk )=-
author
#3 lore raw

Re: [PATCH 1/5] comedi: ni_usb6501: fix NULL-deref in command paths

Quoted 55 lines · Ian Abbott
Quoted 39 lines · Johan Hovold

The driver uses endpoint-sized USB transfer buffers but had no sanity checks on the sizes. This can lead to zero-size-pointer dereferences or overflowed transfer buffers in ni6501_port_command() and ni6501_counter_command() if a (malicious) device has smaller max-packet sizes than expected (or when doing descriptor fuzz testing).

Add the missing sanity checks to probe().

Fixes a03bb00e50ab ("staging: comedi: add NI USB-6501 support")
Cc [email protected] # 3.18
Cc Luca Ellero <[email protected]>
Signed-off-by Johan Hovold <[email protected]>
---
  drivers/comedi/drivers/ni_usb6501.c | 8 ++++++++
  1 file changed, 8 insertions(+)
drivers/comedi/drivers/ni_usb6501.c +6 -0
index 5b6d9d783b2f..eb2e5c23f25d 100644
@@ -144,6 +144,10 @@ static const u8 READ_COUNTER_RESPONSE[]	= {0x00, 0x01, 0x00, 0x10,
  					   0x00, 0x00, 0x00, 0x02,
  					   0x00, 0x00, 0x00, 0x00};
 
+/* Largest supported packets */
+static const size_t TX_MAX_SIZE	= sizeof(SET_PORT_DIR_REQUEST);
+static const size_t RX_MAX_SIZE	= sizeof(READ_PORT_RESPONSE);
+
  enum commands {
  	READ_PORT,
  	WRITE_PORT,

@@ -486,12 +490,16 @@ static int ni6501_find_endpoints(struct comedi_device *dev)
  		ep_desc = &iface_desc->endpoint[i].desc;
 
  		if (usb_endpoint_is_bulk_in(ep_desc)) {
+			if (usb_endpoint_maxp(ep_desc) < RX_MAX_SIZE)
+				continue;
  			if (!devpriv->ep_rx)

drivers/comedi/drivers/ni_usb6501.c static int ni6501_find_endpoints(struct comedi_device *dev) · line 505

Quoted 10 lines
drivers/comedi/drivers/ni_usb6501.c +2 -0
  				devpriv->ep_rx = ep_desc;
  			continue;
  		}
 
  		if (usb_endpoint_is_bulk_out(ep_desc)) {
+			if (usb_endpoint_maxp(ep_desc) < TX_MAX_SIZE)
+				continue;
  			if (!devpriv->ep_tx)
  				devpriv->ep_tx = ep_desc;
  			continue;

Perhaps it should return an error if the first encountered bulk-in endpoint has the wrong size or the first encountered bulk-out endpoint has the wrong size. Something like:

Quoted 6 lines
		if (usb_endpoint_is_bulk_in(ep_desc)) {
			if (!devpriv->ep_rx) {
				if (usb_endpoint_maxp(ep_desc) < RX_MAX_SIZE)
					break;
			}
			continue;

This is too convoluted, but I can move the max-packet sanity checks after the endpoint look-ups instead.

It doesn't really matter in the end as the real devices presumably only have two bulk endpoints.

Johan

author
#4 lore raw

PATCH 2/5 comedi: dt9812: fix DMA buffers on stack

In reply to Johan Hovold

USB transfer buffers are typically mapped for DMA and must not be allocated on the stack or transfers will fail.

Allocate proper transfer buffers in the various command helpers and return an error on short transfers instead of acting on random stack data.

Note that this also fixes a stack info leak on systems where DMA is not used as 32 bytes are always sent to the device regardless of how short the command is.

Fixes 63274cd7d38a ("Staging: comedi: add usb dt9812 driver")
Cc [email protected] # 2.6.29
Signed-off-by Johan Hovold <[email protected]>
---
 drivers/comedi/drivers/dt9812.c | 109 ++++++++++++++++++++++++--------
 1 file changed, 82 insertions(+), 27 deletions(-)
drivers/comedi/drivers/dt9812.c +82 -27
index 634f57730c1e..f15c306f2d06 100644
@@ -32,6 +32,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/errno.h>
+#include <linux/slab.h>
 #include <linux/uaccess.h>
 
 #include "../comedi_usb.h"

@@ -237,22 +238,41 @@ static int dt9812_read_info(struct comedi_device *dev,
 {
 	struct usb_device *usb = comedi_to_usb_dev(dev);
 	struct dt9812_private *devpriv = dev->private;
-	struct dt9812_usb_cmd cmd;
+	struct dt9812_usb_cmd *cmd;
 	int count, ret;
+	u8 *tbuf;
 
-	cmd.cmd = cpu_to_le32(DT9812_R_FLASH_DATA);
-	cmd.u.flash_data_info.address =
+	cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
+	if (!cmd)
+		return -ENOMEM;
+
+	cmd->cmd = cpu_to_le32(DT9812_R_FLASH_DATA);
+	cmd->u.flash_data_info.address =
 	    cpu_to_le16(DT9812_DIAGS_BOARD_INFO_ADDR + offset);
-	cmd.u.flash_data_info.numbytes = cpu_to_le16(buf_size);
+	cmd->u.flash_data_info.numbytes = cpu_to_le16(buf_size);
 
 	/* DT9812 only responds to 32 byte writes!! */
 	ret = usb_bulk_msg(usb, usb_sndbulkpipe(usb, devpriv->cmd_wr.addr),
-			   &cmd, 32, &count, DT9812_USB_TIMEOUT);
+			   cmd, sizeof(*cmd), &count, DT9812_USB_TIMEOUT);
+	kfree(cmd);
 	if (ret)
 		return ret;
 
-	return usb_bulk_msg(usb, usb_rcvbulkpipe(usb, devpriv->cmd_rd.addr),
-			    buf, buf_size, &count, DT9812_USB_TIMEOUT);
+	tbuf = kmalloc(buf_size, GFP_KERNEL);
+	if (!tbuf)
+		return -ENOMEM;
+
+	ret = usb_bulk_msg(usb, usb_rcvbulkpipe(usb, devpriv->cmd_rd.addr),
+			   tbuf, buf_size, &count, DT9812_USB_TIMEOUT);
+	if (!ret) {
+		if (count == buf_size)
+			memcpy(buf, tbuf, buf_size);
+		else
+			ret = -EREMOTEIO;
+	}
+	kfree(tbuf);
+
+	return ret;
 }
 
 static int dt9812_read_multiple_registers(struct comedi_device *dev,

@@ -261,22 +281,41 @@ static int dt9812_read_multiple_registers(struct comedi_device *dev,
 {
 	struct usb_device *usb = comedi_to_usb_dev(dev);
 	struct dt9812_private *devpriv = dev->private;
-	struct dt9812_usb_cmd cmd;
+	struct dt9812_usb_cmd *cmd;
 	int i, count, ret;
+	u8 *buf;
 
-	cmd.cmd = cpu_to_le32(DT9812_R_MULTI_BYTE_REG);
-	cmd.u.read_multi_info.count = reg_count;
+	cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
+	if (!cmd)
+		return -ENOMEM;
+
+	cmd->cmd = cpu_to_le32(DT9812_R_MULTI_BYTE_REG);
+	cmd->u.read_multi_info.count = reg_count;
 	for (i = 0; i < reg_count; i++)
-		cmd.u.read_multi_info.address[i] = address[i];
+		cmd->u.read_multi_info.address[i] = address[i];
 
 	/* DT9812 only responds to 32 byte writes!! */
 	ret = usb_bulk_msg(usb, usb_sndbulkpipe(usb, devpriv->cmd_wr.addr),
-			   &cmd, 32, &count, DT9812_USB_TIMEOUT);
+			   cmd, sizeof(*cmd), &count, DT9812_USB_TIMEOUT);
+	kfree(cmd);
 	if (ret)
 		return ret;
 
-	return usb_bulk_msg(usb, usb_rcvbulkpipe(usb, devpriv->cmd_rd.addr),
-			    value, reg_count, &count, DT9812_USB_TIMEOUT);
+	buf = kmalloc(reg_count, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = usb_bulk_msg(usb, usb_rcvbulkpipe(usb, devpriv->cmd_rd.addr),
+			   buf, reg_count, &count, DT9812_USB_TIMEOUT);
+	if (!ret) {
+		if (count == reg_count)
+			memcpy(value, buf, reg_count);
+		else
+			ret = -EREMOTEIO;
+	}
+	kfree(buf);
+
+	return ret;
 }
 
 static int dt9812_write_multiple_registers(struct comedi_device *dev,

@@ -285,19 +324,27 @@ static int dt9812_write_multiple_registers(struct comedi_device *dev,
 {
 	struct usb_device *usb = comedi_to_usb_dev(dev);
 	struct dt9812_private *devpriv = dev->private;
-	struct dt9812_usb_cmd cmd;
+	struct dt9812_usb_cmd *cmd;
 	int i, count;
+	int ret;
+
+	cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
+	if (!cmd)
+		return -ENOMEM;
 
-	cmd.cmd = cpu_to_le32(DT9812_W_MULTI_BYTE_REG);
-	cmd.u.read_multi_info.count = reg_count;
+	cmd->cmd = cpu_to_le32(DT9812_W_MULTI_BYTE_REG);
+	cmd->u.read_multi_info.count = reg_count;
 	for (i = 0; i < reg_count; i++) {
-		cmd.u.write_multi_info.write[i].address = address[i];
-		cmd.u.write_multi_info.write[i].value = value[i];
+		cmd->u.write_multi_info.write[i].address = address[i];
+		cmd->u.write_multi_info.write[i].value = value[i];
 	}
 
 	/* DT9812 only responds to 32 byte writes!! */
-	return usb_bulk_msg(usb, usb_sndbulkpipe(usb, devpriv->cmd_wr.addr),
-			    &cmd, 32, &count, DT9812_USB_TIMEOUT);
+	ret = usb_bulk_msg(usb, usb_sndbulkpipe(usb, devpriv->cmd_wr.addr),
+			   cmd, sizeof(*cmd), &count, DT9812_USB_TIMEOUT);
+	kfree(cmd);
+
+	return ret;
 }
 
 static int dt9812_rmw_multiple_registers(struct comedi_device *dev,

@@ -306,17 +353,25 @@ static int dt9812_rmw_multiple_registers(struct comedi_device *dev,
 {
 	struct usb_device *usb = comedi_to_usb_dev(dev);
 	struct dt9812_private *devpriv = dev->private;
-	struct dt9812_usb_cmd cmd;
+	struct dt9812_usb_cmd *cmd;
 	int i, count;
+	int ret;
+
+	cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
+	if (!cmd)
+		return -ENOMEM;
 
-	cmd.cmd = cpu_to_le32(DT9812_RMW_MULTI_BYTE_REG);
-	cmd.u.rmw_multi_info.count = reg_count;
+	cmd->cmd = cpu_to_le32(DT9812_RMW_MULTI_BYTE_REG);
+	cmd->u.rmw_multi_info.count = reg_count;
 	for (i = 0; i < reg_count; i++)
-		cmd.u.rmw_multi_info.rmw[i] = rmw[i];
+		cmd->u.rmw_multi_info.rmw[i] = rmw[i];
 
 	/* DT9812 only responds to 32 byte writes!! */
-	return usb_bulk_msg(usb, usb_sndbulkpipe(usb, devpriv->cmd_wr.addr),
-			    &cmd, 32, &count, DT9812_USB_TIMEOUT);
+	ret = usb_bulk_msg(usb, usb_sndbulkpipe(usb, devpriv->cmd_wr.addr),
+			   cmd, sizeof(*cmd), &count, DT9812_USB_TIMEOUT);
+	kfree(cmd);
+
+	return ret;
 }
 
 static int dt9812_digital_in(struct comedi_device *dev, u8 *bits)
Signature · 1 line
2.32.0
maintainer
#5 lore raw

Re: [PATCH 2/5] comedi: dt9812: fix DMA buffers on stack

Quoted 67 lines · Johan Hovold

USB transfer buffers are typically mapped for DMA and must not be allocated on the stack or transfers will fail.

Allocate proper transfer buffers in the various command helpers and return an error on short transfers instead of acting on random stack data.

Note that this also fixes a stack info leak on systems where DMA is not used as 32 bytes are always sent to the device regardless of how short the command is.

Fixes 63274cd7d38a ("Staging: comedi: add usb dt9812 driver")
Cc [email protected] # 2.6.29
Signed-off-by Johan Hovold <[email protected]>
---
  drivers/comedi/drivers/dt9812.c | 109 ++++++++++++++++++++++++--------
  1 file changed, 82 insertions(+), 27 deletions(-)
drivers/comedi/drivers/dt9812.c +18 -7
index 634f57730c1e..f15c306f2d06 100644
@@ -32,6 +32,7 @@
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/errno.h>
+#include <linux/slab.h>
  #include <linux/uaccess.h>
 
  #include "../comedi_usb.h"

@@ -237,22 +238,41 @@ static int dt9812_read_info(struct comedi_device *dev,
  {
  	struct usb_device *usb = comedi_to_usb_dev(dev);
  	struct dt9812_private *devpriv = dev->private;
-	struct dt9812_usb_cmd cmd;
+	struct dt9812_usb_cmd *cmd;
  	int count, ret;
+	u8 *tbuf;
 
-	cmd.cmd = cpu_to_le32(DT9812_R_FLASH_DATA);
-	cmd.u.flash_data_info.address =
+	cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
+	if (!cmd)
+		return -ENOMEM;
+
+	cmd->cmd = cpu_to_le32(DT9812_R_FLASH_DATA);
+	cmd->u.flash_data_info.address =
  	    cpu_to_le16(DT9812_DIAGS_BOARD_INFO_ADDR + offset);
-	cmd.u.flash_data_info.numbytes = cpu_to_le16(buf_size);
+	cmd->u.flash_data_info.numbytes = cpu_to_le16(buf_size);
 
  	/* DT9812 only responds to 32 byte writes!! */
  	ret = usb_bulk_msg(usb, usb_sndbulkpipe(usb, devpriv->cmd_wr.addr),
-			   &cmd, 32, &count, DT9812_USB_TIMEOUT);
+			   cmd, sizeof(*cmd), &count, DT9812_USB_TIMEOUT);
+	kfree(cmd);
  	if (ret)
  		return ret;
 
-	return usb_bulk_msg(usb, usb_rcvbulkpipe(usb, devpriv->cmd_rd.addr),
-			    buf, buf_size, &count, DT9812_USB_TIMEOUT);
+	tbuf = kmalloc(buf_size, GFP_KERNEL);
+	if (!tbuf)
+		return -ENOMEM;
+
+	ret = usb_bulk_msg(usb, usb_rcvbulkpipe(usb, devpriv->cmd_rd.addr),
+			   tbuf, buf_size, &count, DT9812_USB_TIMEOUT);

drivers/comedi/drivers/dt9812.c static int dt9812_read_info(struct comedi_device *dev, · line 276

Quoted 10 lines
drivers/comedi/drivers/dt9812.c +9 -0
+	if (!ret) {
+		if (count == buf_size)
+			memcpy(buf, tbuf, buf_size);
+		else
+			ret = -EREMOTEIO;
+	}
+	kfree(tbuf);
+
+	return ret;
  }

I suggest doing all the allocations up front so it doesn't leave an unread reply message in the unlikely event that the tbuf allocation fails. (It could even allocate a single buffer for both the command and the reply since they are not needed at the same time.)

Ditto for the other functions in the patch.

Signature · 4 lines
-=( Ian Abbott <[email protected]> || MEV Ltd. is a company  )=-
-=( registered in England & Wales.  Regd. number: 02862268.  )=-
-=( Regd. addr.: S11 & 12 Building 67, Europa Business Park, )=-
-=( Bird Hall Lane, STOCKPORT, SK3 0XA, UK. || www.mev.co.uk )=-
author
#6 lore raw

Re: [PATCH 2/5] comedi: dt9812: fix DMA buffers on stack

Quoted 75 lines · Ian Abbott
Quoted 74 lines · Johan Hovold

USB transfer buffers are typically mapped for DMA and must not be allocated on the stack or transfers will fail.

Allocate proper transfer buffers in the various command helpers and return an error on short transfers instead of acting on random stack data.

Note that this also fixes a stack info leak on systems where DMA is not used as 32 bytes are always sent to the device regardless of how short the command is.

Fixes 63274cd7d38a ("Staging: comedi: add usb dt9812 driver")
Cc [email protected] # 2.6.29
Signed-off-by Johan Hovold <[email protected]>
---
  drivers/comedi/drivers/dt9812.c | 109 ++++++++++++++++++++++++--------
  1 file changed, 82 insertions(+), 27 deletions(-)
drivers/comedi/drivers/dt9812.c +25 -7
index 634f57730c1e..f15c306f2d06 100644
@@ -32,6 +32,7 @@
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/errno.h>
+#include <linux/slab.h>
  #include <linux/uaccess.h>
 
  #include "../comedi_usb.h"

@@ -237,22 +238,41 @@ static int dt9812_read_info(struct comedi_device *dev,
  {
  	struct usb_device *usb = comedi_to_usb_dev(dev);
  	struct dt9812_private *devpriv = dev->private;
-	struct dt9812_usb_cmd cmd;
+	struct dt9812_usb_cmd *cmd;
  	int count, ret;
+	u8 *tbuf;
 
-	cmd.cmd = cpu_to_le32(DT9812_R_FLASH_DATA);
-	cmd.u.flash_data_info.address =
+	cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
+	if (!cmd)
+		return -ENOMEM;
+
+	cmd->cmd = cpu_to_le32(DT9812_R_FLASH_DATA);
+	cmd->u.flash_data_info.address =
  	    cpu_to_le16(DT9812_DIAGS_BOARD_INFO_ADDR + offset);
-	cmd.u.flash_data_info.numbytes = cpu_to_le16(buf_size);
+	cmd->u.flash_data_info.numbytes = cpu_to_le16(buf_size);
 
  	/* DT9812 only responds to 32 byte writes!! */
  	ret = usb_bulk_msg(usb, usb_sndbulkpipe(usb, devpriv->cmd_wr.addr),
-			   &cmd, 32, &count, DT9812_USB_TIMEOUT);
+			   cmd, sizeof(*cmd), &count, DT9812_USB_TIMEOUT);
+	kfree(cmd);
  	if (ret)
  		return ret;
 
-	return usb_bulk_msg(usb, usb_rcvbulkpipe(usb, devpriv->cmd_rd.addr),
-			    buf, buf_size, &count, DT9812_USB_TIMEOUT);
+	tbuf = kmalloc(buf_size, GFP_KERNEL);
+	if (!tbuf)
+		return -ENOMEM;
+
+	ret = usb_bulk_msg(usb, usb_rcvbulkpipe(usb, devpriv->cmd_rd.addr),
+			   tbuf, buf_size, &count, DT9812_USB_TIMEOUT);
+	if (!ret) {
+		if (count == buf_size)
+			memcpy(buf, tbuf, buf_size);
+		else
+			ret = -EREMOTEIO;
+	}
+	kfree(tbuf);
Quoted 8 lines

drivers/comedi/drivers/dt9812.c static int dt9812_read_info(struct comedi_device *dev, · line 276

Quoted 3 lines
drivers/comedi/drivers/dt9812.c +2 -0
+
+	return ret;
  }

I suggest doing all the allocations up front so it doesn't leave an unread reply message in the unlikely event that the tbuf allocation fails. (It could even allocate a single buffer for both the command and the reply since they are not needed at the same time.)

These small allocations will currently never fail, but if they ever were to, there are other allocations done in the I/O path which would have the same effect if they failed. And if this ever happens, you certainly have bigger problems than worrying about the state of this device. :)

That said, I'll see if I can reuse a single buffer without things getting too messy.

Johan

author
#7 lore raw

PATCH 3/5 comedi: vmk80xx: fix transfer-buffer overflows

In reply to Johan Hovold

The driver uses endpoint-sized USB transfer buffers but up until recently had no sanity checks on the sizes.

Commit e1f13c879a7c ("staging: comedi: check validity of wMaxPacketSize of usb endpoints found") inadvertently fixed NULL-pointer dereferences when accessing the transfer buffers in case a malicious device has a zero wMaxPacketSize.

Make sure to allocate buffers large enough to handle also the other accesses that are done without a size check (e.g. byte 18 in vmk80xx_cnt_insn_read() for the VMK8061_MODEL) to avoid writing beyond the buffers, for example, when doing descriptor fuzzing.

The original driver was for a low-speed device with 8-byte buffers. Support was later added for a device that uses bulk transfers and is presumably a full-speed device with a maximum 64-byte wMaxPacketSize.

Fixes 985cafccbf9b ("Staging: Comedi: vmk80xx: Add k8061 support")
Cc [email protected] # 2.6.31
Signed-off-by Johan Hovold <[email protected]>
---
 drivers/comedi/drivers/vmk80xx.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
drivers/comedi/drivers/vmk80xx.c +4 -2
index 9f920819cd74..f2c1572d0cd7 100644
@@ -90,6 +90,8 @@ enum {
 #define IC3_VERSION		BIT(0)
 #define IC6_VERSION		BIT(1)
 
+#define MIN_BUF_SIZE		64
+
 enum vmk80xx_model {
 	VMK8055_MODEL,
 	VMK8061_MODEL

@@ -678,12 +680,12 @@ static int vmk80xx_alloc_usb_buffers(struct comedi_device *dev)
 	struct vmk80xx_private *devpriv = dev->private;
 	size_t size;
 
-	size = usb_endpoint_maxp(devpriv->ep_rx);
+	size = max(usb_endpoint_maxp(devpriv->ep_rx), MIN_BUF_SIZE);
 	devpriv->usb_rx_buf = kzalloc(size, GFP_KERNEL);
 	if (!devpriv->usb_rx_buf)
 		return -ENOMEM;
 
-	size = usb_endpoint_maxp(devpriv->ep_tx);
+	size = max(usb_endpoint_maxp(devpriv->ep_rx), MIN_BUF_SIZE);
 	devpriv->usb_tx_buf = kzalloc(size, GFP_KERNEL);
 	if (!devpriv->usb_tx_buf)
 		return -ENOMEM;
Signature · 1 line
2.32.0
maintainer Reviewed-by on v1 3/5
#8 lore raw

Re: [PATCH 3/5] comedi: vmk80xx: fix transfer-buffer overflows

Quoted 43 lines · Johan Hovold

The driver uses endpoint-sized USB transfer buffers but up until recently had no sanity checks on the sizes.

Commit e1f13c879a7c ("staging: comedi: check validity of wMaxPacketSize of usb endpoints found") inadvertently fixed NULL-pointer dereferences when accessing the transfer buffers in case a malicious device has a zero wMaxPacketSize.

Make sure to allocate buffers large enough to handle also the other accesses that are done without a size check (e.g. byte 18 in vmk80xx_cnt_insn_read() for the VMK8061_MODEL) to avoid writing beyond the buffers, for example, when doing descriptor fuzzing.

The original driver was for a low-speed device with 8-byte buffers. Support was later added for a device that uses bulk transfers and is presumably a full-speed device with a maximum 64-byte wMaxPacketSize.

Fixes 985cafccbf9b ("Staging: Comedi: vmk80xx: Add k8061 support")
Cc [email protected] # 2.6.31
Signed-off-by Johan Hovold <[email protected]>
---
  drivers/comedi/drivers/vmk80xx.c | 6 ++++--
  1 file changed, 4 insertions(+), 2 deletions(-)
drivers/comedi/drivers/vmk80xx.c +2 -1
index 9f920819cd74..f2c1572d0cd7 100644
@@ -90,6 +90,8 @@ enum {
  #define IC3_VERSION		BIT(0)
  #define IC6_VERSION		BIT(1)
 
+#define MIN_BUF_SIZE		64
+
  enum vmk80xx_model {
  	VMK8055_MODEL,
  	VMK8061_MODEL

@@ -678,12 +680,12 @@ static int vmk80xx_alloc_usb_buffers(struct comedi_device *dev)
  	struct vmk80xx_private *devpriv = dev->private;
  	size_t size;
 
-	size = usb_endpoint_maxp(devpriv->ep_rx);

drivers/comedi/drivers/vmk80xx.c static int vmk80xx_alloc_usb_buffers(struct comedi_device *dev) · line 691

Quoted 10 lines
drivers/comedi/drivers/vmk80xx.c +2 -1
+	size = max(usb_endpoint_maxp(devpriv->ep_rx), MIN_BUF_SIZE);
  	devpriv->usb_rx_buf = kzalloc(size, GFP_KERNEL);
  	if (!devpriv->usb_rx_buf)
  		return -ENOMEM;
 
-	size = usb_endpoint_maxp(devpriv->ep_tx);
+	size = max(usb_endpoint_maxp(devpriv->ep_rx), MIN_BUF_SIZE);
  	devpriv->usb_tx_buf = kzalloc(size, GFP_KERNEL);
  	if (!devpriv->usb_tx_buf)
  		return -ENOMEM;

Looks good, thanks!

Reviewed-by Ian Abbott <[email protected]>
Signature · 4 lines
-=( Ian Abbott <[email protected]> || MEV Ltd. is a company  )=-
-=( registered in England & Wales.  Regd. number: 02862268.  )=-
-=( Regd. addr.: S11 & 12 Building 67, Europa Business Park, )=-
-=( Bird Hall Lane, STOCKPORT, SK3 0XA, UK. || www.mev.co.uk )=-
author
#9 lore raw

PATCH 4/5 comedi: vmk80xx: fix bulk-buffer overflow

In reply to Johan Hovold

The driver is using endpoint-sized buffers but must not assume that the tx and rx buffers are of equal size or a malicious device could overflow the slab-allocated receive buffer when doing bulk transfers.

Fixes 985cafccbf9b ("Staging: Comedi: vmk80xx: Add k8061 support")
Cc [email protected] # 2.6.31
Signed-off-by Johan Hovold <[email protected]>
---
 drivers/comedi/drivers/vmk80xx.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)
drivers/comedi/drivers/vmk80xx.c +7 -9
index f2c1572d0cd7..9c56918e3b76 100644
@@ -159,22 +159,20 @@ static void vmk80xx_do_bulk_msg(struct comedi_device *dev)
 	__u8 rx_addr;
 	unsigned int tx_pipe;
 	unsigned int rx_pipe;
-	size_t size;
+	size_t tx_size;
+	size_t rx_size;
 
 	tx_addr = devpriv->ep_tx->bEndpointAddress;
 	rx_addr = devpriv->ep_rx->bEndpointAddress;
 	tx_pipe = usb_sndbulkpipe(usb, tx_addr);
 	rx_pipe = usb_rcvbulkpipe(usb, rx_addr);
-
-	/*
-	 * The max packet size attributes of the K8061
-	 * input/output endpoints are identical
-	 */
-	size = usb_endpoint_maxp(devpriv->ep_tx);
+	tx_size = usb_endpoint_maxp(devpriv->ep_tx);
+	rx_size = usb_endpoint_maxp(devpriv->ep_rx);
 
 	usb_bulk_msg(usb, tx_pipe, devpriv->usb_tx_buf,
-		     size, NULL, devpriv->ep_tx->bInterval);
-	usb_bulk_msg(usb, rx_pipe, devpriv->usb_rx_buf, size, NULL, HZ * 10);
+		     tx_size, NULL, devpriv->ep_tx->bInterval);
+
+	usb_bulk_msg(usb, rx_pipe, devpriv->usb_rx_buf, rx_size, NULL, HZ * 10);
 }
 
 static int vmk80xx_read_packet(struct comedi_device *dev)
Signature · 1 line
2.32.0
maintainer Reviewed-by on v1 4/5
#10 lore raw

Re: [PATCH 4/5] comedi: vmk80xx: fix bulk-buffer overflow

Quoted 36 lines · Johan Hovold

The driver is using endpoint-sized buffers but must not assume that the tx and rx buffers are of equal size or a malicious device could overflow the slab-allocated receive buffer when doing bulk transfers.

Fixes 985cafccbf9b ("Staging: Comedi: vmk80xx: Add k8061 support")
Cc [email protected] # 2.6.31
Signed-off-by Johan Hovold <[email protected]>
---
  drivers/comedi/drivers/vmk80xx.c | 16 +++++++---------
  1 file changed, 7 insertions(+), 9 deletions(-)
drivers/comedi/drivers/vmk80xx.c +4 -7
index f2c1572d0cd7..9c56918e3b76 100644
@@ -159,22 +159,20 @@ static void vmk80xx_do_bulk_msg(struct comedi_device *dev)
  	__u8 rx_addr;
  	unsigned int tx_pipe;
  	unsigned int rx_pipe;
-	size_t size;
+	size_t tx_size;
+	size_t rx_size;
 
  	tx_addr = devpriv->ep_tx->bEndpointAddress;
  	rx_addr = devpriv->ep_rx->bEndpointAddress;
  	tx_pipe = usb_sndbulkpipe(usb, tx_addr);
  	rx_pipe = usb_rcvbulkpipe(usb, rx_addr);
-
-	/*
-	 * The max packet size attributes of the K8061
-	 * input/output endpoints are identical
-	 */
-	size = usb_endpoint_maxp(devpriv->ep_tx);
+	tx_size = usb_endpoint_maxp(devpriv->ep_tx);
+	rx_size = usb_endpoint_maxp(devpriv->ep_rx);

drivers/comedi/drivers/vmk80xx.c static void vmk80xx_do_bulk_msg(struct comedi_device *dev) · line 178

Quoted 10 lines
drivers/comedi/drivers/vmk80xx.c +3 -2
 
  	usb_bulk_msg(usb, tx_pipe, devpriv->usb_tx_buf,
-		     size, NULL, devpriv->ep_tx->bInterval);
-	usb_bulk_msg(usb, rx_pipe, devpriv->usb_rx_buf, size, NULL, HZ * 10);
+		     tx_size, NULL, devpriv->ep_tx->bInterval);
+
+	usb_bulk_msg(usb, rx_pipe, devpriv->usb_rx_buf, rx_size, NULL, HZ * 10);
  }
 
  static int vmk80xx_read_packet(struct comedi_device *dev)

Looks good, thanks!

Reviewed-by Ian Abbott <[email protected]>
Signature · 4 lines
-=( Ian Abbott <[email protected]> || MEV Ltd. is a company  )=-
-=( registered in England & Wales.  Regd. number: 02862268.  )=-
-=( Regd. addr.: S11 & 12 Building 67, Europa Business Park, )=-
-=( Bird Hall Lane, STOCKPORT, SK3 0XA, UK. || www.mev.co.uk )=-
author
#11 lore raw

PATCH 5/5 comedi: vmk80xx: fix bulk and interrupt message timeouts

In reply to Johan Hovold

USB bulk and interrupt message timeouts are specified in milliseconds and should specifically not vary with CONFIG_HZ.

Note that the bulk-out transfer timeout was set to the endpoint bInterval value, which should be ignored for bulk endpoints and is typically set to zero. This meant that a failing bulk-out transfer would never time out.

Assume that the 10 second timeout used for all other transfers is more than enough also for the bulk-out endpoint.

Fixes 985cafccbf9b ("Staging: Comedi: vmk80xx: Add k8061 support")
Fixes 951348b37738 ("staging: comedi: vmk80xx: wait for URBs to complete")
Cc [email protected] # 2.6.31
Signed-off-by Johan Hovold <[email protected]>
---
 drivers/comedi/drivers/vmk80xx.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)
drivers/comedi/drivers/vmk80xx.c +7 -5
index 9c56918e3b76..4b00a9ea611a 100644
@@ -91,6 +91,7 @@ enum {
 #define IC6_VERSION		BIT(1)
 
 #define MIN_BUF_SIZE		64
+#define PACKET_TIMEOUT		10000	/* ms */
 
 enum vmk80xx_model {
 	VMK8055_MODEL,

@@ -169,10 +170,11 @@ static void vmk80xx_do_bulk_msg(struct comedi_device *dev)
 	tx_size = usb_endpoint_maxp(devpriv->ep_tx);
 	rx_size = usb_endpoint_maxp(devpriv->ep_rx);
 
-	usb_bulk_msg(usb, tx_pipe, devpriv->usb_tx_buf,
-		     tx_size, NULL, devpriv->ep_tx->bInterval);
+	usb_bulk_msg(usb, tx_pipe, devpriv->usb_tx_buf, tx_size, NULL,
+		     PACKET_TIMEOUT);
 
-	usb_bulk_msg(usb, rx_pipe, devpriv->usb_rx_buf, rx_size, NULL, HZ * 10);
+	usb_bulk_msg(usb, rx_pipe, devpriv->usb_rx_buf, rx_size, NULL,
+		     PACKET_TIMEOUT);
 }
 
 static int vmk80xx_read_packet(struct comedi_device *dev)

@@ -191,7 +193,7 @@ static int vmk80xx_read_packet(struct comedi_device *dev)
 	pipe = usb_rcvintpipe(usb, ep->bEndpointAddress);
 	return usb_interrupt_msg(usb, pipe, devpriv->usb_rx_buf,
 				 usb_endpoint_maxp(ep), NULL,
-				 HZ * 10);
+				 PACKET_TIMEOUT);
 }
 
 static int vmk80xx_write_packet(struct comedi_device *dev, int cmd)

@@ -212,7 +214,7 @@ static int vmk80xx_write_packet(struct comedi_device *dev, int cmd)
 	pipe = usb_sndintpipe(usb, ep->bEndpointAddress);
 	return usb_interrupt_msg(usb, pipe, devpriv->usb_tx_buf,
 				 usb_endpoint_maxp(ep), NULL,
-				 HZ * 10);
+				 PACKET_TIMEOUT);
 }
 
 static int vmk80xx_reset_device(struct comedi_device *dev)
Signature · 1 line
2.32.0
maintainer Reviewed-by on v1 5/5
#12 lore raw

Re: [PATCH 5/5] comedi: vmk80xx: fix bulk and interrupt message timeouts

Quoted 57 lines · Johan Hovold

USB bulk and interrupt message timeouts are specified in milliseconds and should specifically not vary with CONFIG_HZ.

Note that the bulk-out transfer timeout was set to the endpoint bInterval value, which should be ignored for bulk endpoints and is typically set to zero. This meant that a failing bulk-out transfer would never time out.

Assume that the 10 second timeout used for all other transfers is more than enough also for the bulk-out endpoint.

Fixes 985cafccbf9b ("Staging: Comedi: vmk80xx: Add k8061 support")
Fixes 951348b37738 ("staging: comedi: vmk80xx: wait for URBs to complete")
Cc [email protected] # 2.6.31
Signed-off-by Johan Hovold <[email protected]>
---
  drivers/comedi/drivers/vmk80xx.c | 12 +++++++-----
  1 file changed, 7 insertions(+), 5 deletions(-)
drivers/comedi/drivers/vmk80xx.c +6 -4
index 9c56918e3b76..4b00a9ea611a 100644
@@ -91,6 +91,7 @@ enum {
  #define IC6_VERSION		BIT(1)
 
  #define MIN_BUF_SIZE		64
+#define PACKET_TIMEOUT		10000	/* ms */
 
  enum vmk80xx_model {
  	VMK8055_MODEL,

@@ -169,10 +170,11 @@ static void vmk80xx_do_bulk_msg(struct comedi_device *dev)
  	tx_size = usb_endpoint_maxp(devpriv->ep_tx);
  	rx_size = usb_endpoint_maxp(devpriv->ep_rx);
 
-	usb_bulk_msg(usb, tx_pipe, devpriv->usb_tx_buf,
-		     tx_size, NULL, devpriv->ep_tx->bInterval);
+	usb_bulk_msg(usb, tx_pipe, devpriv->usb_tx_buf, tx_size, NULL,
+		     PACKET_TIMEOUT);
 
-	usb_bulk_msg(usb, rx_pipe, devpriv->usb_rx_buf, rx_size, NULL, HZ * 10);
+	usb_bulk_msg(usb, rx_pipe, devpriv->usb_rx_buf, rx_size, NULL,
+		     PACKET_TIMEOUT);
  }
 
  static int vmk80xx_read_packet(struct comedi_device *dev)

@@ -191,7 +193,7 @@ static int vmk80xx_read_packet(struct comedi_device *dev)
  	pipe = usb_rcvintpipe(usb, ep->bEndpointAddress);
  	return usb_interrupt_msg(usb, pipe, devpriv->usb_rx_buf,
  				 usb_endpoint_maxp(ep), NULL,
-				 HZ * 10);
+				 PACKET_TIMEOUT);
  }
 
  static int vmk80xx_write_packet(struct comedi_device *dev, int cmd)

drivers/comedi/drivers/vmk80xx.c static int vmk80xx_write_packet(struct comedi_device *dev, int cmd) · line 220

Quoted 8 lines
drivers/comedi/drivers/vmk80xx.c +1 -1
@@ -212,7 +214,7 @@ static int vmk80xx_write_packet(struct comedi_device *dev, int cmd)
  	pipe = usb_sndintpipe(usb, ep->bEndpointAddress);
  	return usb_interrupt_msg(usb, pipe, devpriv->usb_tx_buf,
  				 usb_endpoint_maxp(ep), NULL,
-				 HZ * 10);
+				 PACKET_TIMEOUT);
  }
 
  static int vmk80xx_reset_device(struct comedi_device *dev)

Looks good, thanks!

Reviewed-by Ian Abbott <[email protected]>
Signature · 4 lines
-=( Ian Abbott <[email protected]> || MEV Ltd. is a company  )=-
-=( registered in England & Wales.  Regd. number: 02862268.  )=-
-=( Regd. addr.: S11 & 12 Building 67, Europa Business Park, )=-
-=( Bird Hall Lane, STOCKPORT, SK3 0XA, UK. || www.mev.co.uk )=-