All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
To: Evgeny Novikov <novikov@ispras.ru>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>,
	linux-media <linux-media@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	"ldv-project@linuxtesting.org" <ldv-project@linuxtesting.org>
Subject: Re: [PATCH] media: davinci: vpif_capture: fix potential double free
Date: Fri, 24 Jul 2020 23:05:40 +0100	[thread overview]
Message-ID: <CA+V-a8tUmMnb8x=GPXJ8QGLJg5qGP+DP+F9EbUrDfUbrxWnkag@mail.gmail.com> (raw)
In-Reply-To: <20927111595619342@mail.yandex.ru>

Hi Evgeny,

On Fri, Jul 24, 2020 at 9:00 PM Evgeny Novikov <novikov@ispras.ru> 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" <prabhakar.csengg@gmail.com>:
> > Hi Evgeny,
> >
> > Thank you for the patch.
> >
> > On Thu, Jul 23, 2020 at 6:04 PM Evgeny Novikov <novikov@ispras.ru> 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 <novikov@ispras.ru>
> >>  ---
> >>   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

  reply	other threads:[~2020-07-24 22:06 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-23 17:04 Evgeny Novikov
2020-07-24 14:16 ` Lad, Prabhakar
2020-07-24 20:00   ` Evgeny Novikov
2020-07-24 22:05     ` Lad, Prabhakar [this message]
2020-08-02 18:38       ` Evgeny Novikov
2020-07-23 20:15 Markus Elfring
2020-07-23 20:15 ` Markus Elfring
2020-07-24 20:08 ` Evgeny Novikov
2020-07-24 20:08   ` Evgeny Novikov

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CA+V-a8tUmMnb8x=GPXJ8QGLJg5qGP+DP+F9EbUrDfUbrxWnkag@mail.gmail.com' \
    --to=prabhakar.csengg@gmail.com \
    --cc=ldv-project@linuxtesting.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-media@vger.kernel.org \
    --cc=mchehab@kernel.org \
    --cc=novikov@ispras.ru \
    --subject='Re: [PATCH] media: davinci: vpif_capture: fix potential double free' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.