In case of errors vpif_probe_complete() releases memory for vpif_obj.sd
and unregisters the V4L2 device. But then this is done again by
vpif_probe() itself. The patch removes the cleaning from
vpif_probe_complete().
Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Evgeny Novikov <[email protected]>
---
drivers/media/platform/davinci/vpif_capture.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/drivers/media/platform/davinci/vpif_capture.c b/drivers/media/platform/davinci/vpif_capture.c
index d9ec439faefa..72a0e94e2e21 100644
--- a/drivers/media/platform/davinci/vpif_capture.c
+++ b/drivers/media/platform/davinci/vpif_capture.c
@@ -1482,8 +1482,6 @@ static int vpif_probe_complete(void)
/* Unregister video device */
video_unregister_device(&ch->video_dev);
}
- kfree(vpif_obj.sd);
- v4l2_device_unregister(&vpif_obj.v4l2_dev);
return err;
}
--
2.16.4
> In case of errors vpif_probe_complete() releases memory for vpif_obj.sd
> and unregisters the V4L2 device. But then this is done again by
> vpif_probe() itself. The patch removes the cleaning from
> vpif_probe_complete().
* An imperative wording can be preferred for the change description,
can't it?
* Would you like to add the tag “Fixes” to the commit message?
Regards,
Markus
Hi Evgeny,
Thank you for the patch.
On Thu, Jul 23, 2020 at 6:04 PM Evgeny Novikov <[email protected]> wrote:
>
> In case of errors vpif_probe_complete() releases memory for vpif_obj.sd
> and unregisters the V4L2 device. But then this is done again by
> vpif_probe() itself. The patch removes the cleaning from
> vpif_probe_complete().
>
> Found by Linux Driver Verification project (linuxtesting.org).
>
> Signed-off-by: Evgeny Novikov <[email protected]>
> ---
> drivers/media/platform/davinci/vpif_capture.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/drivers/media/platform/davinci/vpif_capture.c b/drivers/media/platform/davinci/vpif_capture.c
> index d9ec439faefa..72a0e94e2e21 100644
> --- a/drivers/media/platform/davinci/vpif_capture.c
> +++ b/drivers/media/platform/davinci/vpif_capture.c
> @@ -1482,8 +1482,6 @@ static int vpif_probe_complete(void)
> /* Unregister video device */
> video_unregister_device(&ch->video_dev);
> }
> - kfree(vpif_obj.sd);
> - v4l2_device_unregister(&vpif_obj.v4l2_dev);
>
vpif_probe_complete() is a async callback and probe() should have
already completed by then.
Cheers,
--Prabhakar
> return err;
> }
> --
> 2.16.4
>
Hi Lad,
Yet again I can not demonstrate you a nice error trace corresponding to the bug fixed by the patch. Indeed, there is a branch in vpif_probe() that explicitly invokes vpif_probe_complete() and the patch targets the possible issue that can happen during this.
When I developed the patch I saw on vpif_display.ko. It looks very similar regarding things touched by the patch. In particular, it does not free vpif_obj.sd in its vpif_probe_complete(). But now I see that it does this in vpif_remove()!
Do you think that vpif_capture.ko should do the same? If so, I guess that I should fix the patch appropriately since likely it just replaces one (very rare) bug with another one (on a typical execution path).
--
Evgeny Novikov
Linux Verification Center, ISP RAS
http://linuxtesting.org
24.07.2020, 17:17, "Lad, Prabhakar" <[email protected]>:
> Hi Evgeny,
>
> Thank you for the patch.
>
> On Thu, Jul 23, 2020 at 6:04 PM Evgeny Novikov <[email protected]> wrote:
>> In case of errors vpif_probe_complete() releases memory for vpif_obj.sd
>> and unregisters the V4L2 device. But then this is done again by
>> vpif_probe() itself. The patch removes the cleaning from
>> vpif_probe_complete().
>>
>> Found by Linux Driver Verification project (linuxtesting.org).
>>
>> Signed-off-by: Evgeny Novikov <[email protected]>
>> ---
>> drivers/media/platform/davinci/vpif_capture.c | 2 --
>> 1 file changed, 2 deletions(-)
>>
>> diff --git a/drivers/media/platform/davinci/vpif_capture.c b/drivers/media/platform/davinci/vpif_capture.c
>> index d9ec439faefa..72a0e94e2e21 100644
>> --- a/drivers/media/platform/davinci/vpif_capture.c
>> +++ b/drivers/media/platform/davinci/vpif_capture.c
>> @@ -1482,8 +1482,6 @@ static int vpif_probe_complete(void)
>> /* Unregister video device */
>> video_unregister_device(&ch->video_dev);
>> }
>> - kfree(vpif_obj.sd);
>> - v4l2_device_unregister(&vpif_obj.v4l2_dev);
>
> vpif_probe_complete() is a async callback and probe() should have
> already completed by then.
>
> Cheers,
> --Prabhakar
>
>> return err;
>> }
>> --
>> 2.16.4
Hi Markus,
It seems that Lad Prabhakar detected a critical issue introduced by the patch instead of a minor bug fixed by it. So, we should take care of this first, but I will address your notes as well.
--
Evgeny Novikov
Linux Verification Center, ISP RAS
http://linuxtesting.org
23.07.2020, 23:15, "Markus Elfring" <[email protected]>:
>> In case of errors vpif_probe_complete() releases memory for vpif_obj.sd
>> and unregisters the V4L2 device. But then this is done again by
>> vpif_probe() itself. The patch removes the cleaning from
>> vpif_probe_complete().
>
> * An imperative wording can be preferred for the change description,
> can't it?
>
> * Would you like to add the tag “Fixes” to the commit message?
>
> Regards,
> Markus
Hi Evgeny,
On Fri, Jul 24, 2020 at 9:00 PM Evgeny Novikov <[email protected]> wrote:
>
> Hi Lad,
>
> Yet again I can not demonstrate you a nice error trace corresponding to the bug fixed by the patch. Indeed, there is a branch in vpif_probe() that explicitly invokes vpif_probe_complete() and the patch targets the possible issue that can happen during this.
>
> When I developed the patch I saw on vpif_display.ko. It looks very similar regarding things touched by the patch. In particular, it does not free vpif_obj.sd in its vpif_probe_complete(). But now I see that it does this in vpif_remove()!
>
Makes sense.
> Do you think that vpif_capture.ko should do the same? If so, I guess that I should fix the patch appropriately since likely it just replaces one (very rare) bug with another one (on a typical execution path).
>
Yes it should.
Cheers,
--Prabhakar
> --
> Evgeny Novikov
> Linux Verification Center, ISP RAS
> http://linuxtesting.org
>
>
>
> 24.07.2020, 17:17, "Lad, Prabhakar" <[email protected]>:
> > Hi Evgeny,
> >
> > Thank you for the patch.
> >
> > On Thu, Jul 23, 2020 at 6:04 PM Evgeny Novikov <[email protected]> wrote:
> >> In case of errors vpif_probe_complete() releases memory for vpif_obj.sd
> >> and unregisters the V4L2 device. But then this is done again by
> >> vpif_probe() itself. The patch removes the cleaning from
> >> vpif_probe_complete().
> >>
> >> Found by Linux Driver Verification project (linuxtesting.org).
> >>
> >> Signed-off-by: Evgeny Novikov <[email protected]>
> >> ---
> >> drivers/media/platform/davinci/vpif_capture.c | 2 --
> >> 1 file changed, 2 deletions(-)
> >>
> >> diff --git a/drivers/media/platform/davinci/vpif_capture.c b/drivers/media/platform/davinci/vpif_capture.c
> >> index d9ec439faefa..72a0e94e2e21 100644
> >> --- a/drivers/media/platform/davinci/vpif_capture.c
> >> +++ b/drivers/media/platform/davinci/vpif_capture.c
> >> @@ -1482,8 +1482,6 @@ static int vpif_probe_complete(void)
> >> /* Unregister video device */
> >> video_unregister_device(&ch->video_dev);
> >> }
> >> - kfree(vpif_obj.sd);
> >> - v4l2_device_unregister(&vpif_obj.v4l2_dev);
> >
> > vpif_probe_complete() is a async callback and probe() should have
> > already completed by then.
> >
> > Cheers,
> > --Prabhakar
> >
> >> return err;
> >> }
> >> --
> >> 2.16.4
Hi Lad,
25.07.2020, 01:06, "Lad, Prabhakar" <[email protected]>:
> Hi Evgeny,
>
> On Fri, Jul 24, 2020 at 9:00 PM Evgeny Novikov <[email protected]> wrote:
>> Hi Lad,
>>
>> Yet again I can not demonstrate you a nice error trace corresponding to the bug fixed by the patch. Indeed, there is a branch in vpif_probe() that explicitly invokes vpif_probe_complete() and the patch targets the possible issue that can happen during this.
>>
>> When I developed the patch I saw on vpif_display.ko. It looks very similar regarding things touched by the patch. In particular, it does not free vpif_obj.sd in its vpif_probe_complete(). But now I see that it does this in vpif_remove()!
>
> Makes sense.
>
>> Do you think that vpif_capture.ko should do the same? If so, I guess that I should fix the patch appropriately since likely it just replaces one (very rare) bug with another one (on a typical execution path).
>
> Yes it should.
vpif_remove() from vpif_capture.ko already both frees vpif_obj.sd and unregisters the V4L2 device. So, there is no need to fix the patch.
BTW, other drivers, e.g. drivers/media/platform/renesas-ceu.c, do not clean up memory allocated by probe within v4l2_async_notifier_operations.complete as well.
--
Best regards,
Evgeny Novikov
> Cheers,
> --Prabhakar
>
>> --
>> Evgeny Novikov
>> Linux Verification Center, ISP RAS
>> http://linuxtesting.org
>>
>> 24.07.2020, 17:17, "Lad, Prabhakar" <[email protected]>:
>> > Hi Evgeny,
>> >
>> > Thank you for the patch.
>> >
>> > On Thu, Jul 23, 2020 at 6:04 PM Evgeny Novikov <[email protected]> wrote:
>> >> In case of errors vpif_probe_complete() releases memory for vpif_obj.sd
>> >> and unregisters the V4L2 device. But then this is done again by
>> >> vpif_probe() itself. The patch removes the cleaning from
>> >> vpif_probe_complete().
>> >>
>> >> Found by Linux Driver Verification project (linuxtesting.org).
>> >>
>> >> Signed-off-by: Evgeny Novikov <[email protected]>
>> >> ---
>> >> drivers/media/platform/davinci/vpif_capture.c | 2 --
>> >> 1 file changed, 2 deletions(-)
>> >>
>> >> diff --git a/drivers/media/platform/davinci/vpif_capture.c b/drivers/media/platform/davinci/vpif_capture.c
>> >> index d9ec439faefa..72a0e94e2e21 100644
>> >> --- a/drivers/media/platform/davinci/vpif_capture.c
>> >> +++ b/drivers/media/platform/davinci/vpif_capture.c
>> >> @@ -1482,8 +1482,6 @@ static int vpif_probe_complete(void)
>> >> /* Unregister video device */
>> >> video_unregister_device(&ch->video_dev);
>> >> }
>> >> - kfree(vpif_obj.sd);
>> >> - v4l2_device_unregister(&vpif_obj.v4l2_dev);
>> >
>> > vpif_probe_complete() is a async callback and probe() should have
>> > already completed by then.
>> >
>> > Cheers,
>> > --Prabhakar
>> >
>> >> return err;
>> >> }
>> >> --
>> >> 2.16.4