[v2] commdi: pcl726: Prevent invalid irq number

[PATCH V2] commdi: pcl726: Prevent invalid irq number

Posted by Edward Adam Davis 3 months ago

The reproducer passed in an irq number(0x80008000) that was too large,
which triggered the oob.

Added an interrupt number check to prevent users from passing in an irq
number that was too large.

If `it->options[1]` is 31, then `1 << it->options[1]` is still invalid
because it shifts a 1-bit into the sign bit (which is UB in C).
Possible solutions include reducing the upper bound on the
`it->options[1]` value to 30 or lower, or using `1U << it->options[1]`.

The old code would just not attempt to request the IRQ if the
`options[1]` value were invalid.  And it would still configure the
device without interrupts even if the call to `request_irq` returned an
error.  So it would be better to combine this test with the test below.

Fixes: fff46207245c ("staging: comedi: pcl726: enable the interrupt support code")
Cc: <stable@vger.kernel.org> # 5.13+
Reported-by: syzbot+5cd373521edd68bebcb3@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=5cd373521edd68bebcb3
Tested-by: syzbot+5cd373521edd68bebcb3@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
V1 -> V2: combine test with old test

 drivers/comedi/drivers/pcl726.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/comedi/drivers/pcl726.c b/drivers/comedi/drivers/pcl726.c
index 0430630e6ebb..b542896fa0e4 100644
--- a/drivers/comedi/drivers/pcl726.c
+++ b/drivers/comedi/drivers/pcl726.c
@@ -328,7 +328,8 @@ static int pcl726_attach(struct comedi_device *dev,
 	 * Hook up the external trigger source interrupt only if the
 	 * user config option is valid and the board supports interrupts.
 	 */
-	if (it->options[1] && (board->irq_mask & (1 << it->options[1]))) {
+	if (it->options[1] > 0 && it->options[1] < 16 &&
+	    (board->irq_mask & (1U << it->options[1]))) {
 		ret = request_irq(it->options[1], pcl726_interrupt, 0,
 				  dev->board_name, dev);
 		if (ret == 0) {
-- 
2.43.0

Re: [PATCH V2] commdi: pcl726: Prevent invalid irq number

Posted by Ian Abbott 3 months ago

On 07/07/2025 12:43, Edward Adam Davis wrote:
> The reproducer passed in an irq number(0x80008000) that was too large,
> which triggered the oob.
> 
> Added an interrupt number check to prevent users from passing in an irq
> number that was too large.
> 
> If `it->options[1]` is 31, then `1 << it->options[1]` is still invalid
> because it shifts a 1-bit into the sign bit (which is UB in C).
> Possible solutions include reducing the upper bound on the
> `it->options[1]` value to 30 or lower, or using `1U << it->options[1]`.
> 
> The old code would just not attempt to request the IRQ if the
> `options[1]` value were invalid.  And it would still configure the
> device without interrupts even if the call to `request_irq` returned an
> error.  So it would be better to combine this test with the test below.
> 
> Fixes: fff46207245c ("staging: comedi: pcl726: enable the interrupt support code")
> Cc: <stable@vger.kernel.org> # 5.13+
> Reported-by: syzbot+5cd373521edd68bebcb3@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=5cd373521edd68bebcb3
> Tested-by: syzbot+5cd373521edd68bebcb3@syzkaller.appspotmail.com
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> ---
> V1 -> V2: combine test with old test
> 
>   drivers/comedi/drivers/pcl726.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/comedi/drivers/pcl726.c b/drivers/comedi/drivers/pcl726.c
> index 0430630e6ebb..b542896fa0e4 100644
> --- a/drivers/comedi/drivers/pcl726.c
> +++ b/drivers/comedi/drivers/pcl726.c
> @@ -328,7 +328,8 @@ static int pcl726_attach(struct comedi_device *dev,
>   	 * Hook up the external trigger source interrupt only if the
>   	 * user config option is valid and the board supports interrupts.
>   	 */
> -	if (it->options[1] && (board->irq_mask & (1 << it->options[1]))) {
> +	if (it->options[1] > 0 && it->options[1] < 16 &&
> +	    (board->irq_mask & (1U << it->options[1]))) {
>   		ret = request_irq(it->options[1], pcl726_interrupt, 0,
>   				  dev->board_name, dev);
>   		if (ret == 0) {

Looks good apart from the subject line that still has the "comedi" tag 
misspelled.  Please could you fix that?

You can also add my Reviewed-by: line:

Reviewed-by: Ian Abbott <abbotti@mev.co.uk>

Please also Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> because 
I do not have commit access to any pulled git repos.

Thanks!

-- 
-=( Ian Abbott <abbotti@mev.co.uk> || 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 )=-

[PATCH V3] comedi: pcl726: Prevent invalid irq number

Posted by Edward Adam Davis 3 months ago

The reproducer passed in an irq number(0x80008000) that was too large,
which triggered the oob.

Added an interrupt number check to prevent users from passing in an irq
number that was too large.

If `it->options[1]` is 31, then `1 << it->options[1]` is still invalid
because it shifts a 1-bit into the sign bit (which is UB in C).
Possible solutions include reducing the upper bound on the
`it->options[1]` value to 30 or lower, or using `1U << it->options[1]`.

The old code would just not attempt to request the IRQ if the
`options[1]` value were invalid.  And it would still configure the
device without interrupts even if the call to `request_irq` returned an
error.  So it would be better to combine this test with the test below.

Fixes: fff46207245c ("staging: comedi: pcl726: enable the interrupt support code")
Cc: <stable@vger.kernel.org> # 5.13+
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reported-by: syzbot+5cd373521edd68bebcb3@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=5cd373521edd68bebcb3
Tested-by: syzbot+5cd373521edd68bebcb3@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
---
V1 -> V2: combine test with old test
V2 -> V3: fix misspelled

 drivers/comedi/drivers/pcl726.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/comedi/drivers/pcl726.c b/drivers/comedi/drivers/pcl726.c
index 0430630e6ebb..b542896fa0e4 100644
--- a/drivers/comedi/drivers/pcl726.c
+++ b/drivers/comedi/drivers/pcl726.c
@@ -328,7 +328,8 @@ static int pcl726_attach(struct comedi_device *dev,
 	 * Hook up the external trigger source interrupt only if the
 	 * user config option is valid and the board supports interrupts.
 	 */
-	if (it->options[1] && (board->irq_mask & (1 << it->options[1]))) {
+	if (it->options[1] > 0 && it->options[1] < 16 &&
+	    (board->irq_mask & (1U << it->options[1]))) {
 		ret = request_irq(it->options[1], pcl726_interrupt, 0,
 				  dev->board_name, dev);
 		if (ret == 0) {
-- 
2.43.0

[PATCH V3 REPOST] comedi: pcl726: Prevent invalid irq number

Posted by Ian Abbott 2 months, 2 weeks ago

From: Edward Adam Davis <eadavis@qq.com>

The reproducer passed in an irq number(0x80008000) that was too large,
which triggered the oob.

Added an interrupt number check to prevent users from passing in an irq
number that was too large.

If `it->options[1]` is 31, then `1 << it->options[1]` is still invalid
because it shifts a 1-bit into the sign bit (which is UB in C).
Possible solutions include reducing the upper bound on the
`it->options[1]` value to 30 or lower, or using `1U << it->options[1]`.

The old code would just not attempt to request the IRQ if the
`options[1]` value were invalid.  And it would still configure the
device without interrupts even if the call to `request_irq` returned an
error.  So it would be better to combine this test with the test below.

Fixes: fff46207245c ("staging: comedi: pcl726: enable the interrupt support code")
Cc: <stable@vger.kernel.org> # 5.13+
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reported-by: syzbot+5cd373521edd68bebcb3@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=5cd373521edd68bebcb3
Tested-by: syzbot+5cd373521edd68bebcb3@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
---
 drivers/comedi/drivers/pcl726.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/comedi/drivers/pcl726.c b/drivers/comedi/drivers/pcl726.c
index 0430630e6ebb..b542896fa0e4 100644
--- a/drivers/comedi/drivers/pcl726.c
+++ b/drivers/comedi/drivers/pcl726.c
@@ -328,7 +328,8 @@ static int pcl726_attach(struct comedi_device *dev,
 	 * Hook up the external trigger source interrupt only if the
 	 * user config option is valid and the board supports interrupts.
 	 */
-	if (it->options[1] && (board->irq_mask & (1 << it->options[1]))) {
+	if (it->options[1] > 0 && it->options[1] < 16 &&
+	    (board->irq_mask & (1U << it->options[1]))) {
 		ret = request_irq(it->options[1], pcl726_interrupt, 0,
 				  dev->board_name, dev);
 		if (ret == 0) {
-- 
2.47.2

Re: [PATCH V3 REPOST] comedi: pcl726: Prevent invalid irq number

Posted by Ian Abbott 2 months, 2 weeks ago

On 24/07/2025 12:07, Ian Abbott wrote:
> From: Edward Adam Davis <eadavis@qq.com>
> 
> The reproducer passed in an irq number(0x80008000) that was too large,
> which triggered the oob.
> 
> Added an interrupt number check to prevent users from passing in an irq
> number that was too large.
> 
> If `it->options[1]` is 31, then `1 << it->options[1]` is still invalid
> because it shifts a 1-bit into the sign bit (which is UB in C).
> Possible solutions include reducing the upper bound on the
> `it->options[1]` value to 30 or lower, or using `1U << it->options[1]`.
> 
> The old code would just not attempt to request the IRQ if the
> `options[1]` value were invalid.  And it would still configure the
> device without interrupts even if the call to `request_irq` returned an
> error.  So it would be better to combine this test with the test below.
> 
> Fixes: fff46207245c ("staging: comedi: pcl726: enable the interrupt support code")
> Cc: <stable@vger.kernel.org> # 5.13+
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Reported-by: syzbot+5cd373521edd68bebcb3@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=5cd373521edd68bebcb3
> Tested-by: syzbot+5cd373521edd68bebcb3@syzkaller.appspotmail.com
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> Reviewed-by: Ian Abbott <abbotti@mev.co.uk>

I forgot to append the changelog from the original email:

V1 -> V2: combine test with old test
V2 -> V3: fix misspelled

Ian

-- 
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-=( 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 )=-