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From:   Aleksandr Nogikh <nogikh@google.com>
Date:   Wed, 22 Nov 2023 12:39:58 +0100
Message-ID: <CANp29Y5DNhTA8Oi1B2Kdmog-6tbuSL8mz66P7=dHR0hEgGAZnQ@mail.gmail.com>
Subject: Re: [syzbot] KASAN: use-after-free Read in __media_entity_remove_links
To:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc:     syzbot <syzbot+0b0095300dfeb8a83dc8@syzkaller.appspotmail.com>,
        andreyknvl@google.com, linux-kernel@vger.kernel.org,
        linux-media@vger.kernel.org, linux-usb@vger.kernel.org,
        mchehab@kernel.org, sakari.ailus@linux.intel.com,
        syzkaller-bugs@googlegroups.com
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Thanks for reporting the problem!

Syzbot looked at the last ~1.5 years of commit history to find the
commit, which is almost always enough, but not in this particular
case.

I've filed https://github.com/google/syzkaller/issues/4347 to fix the
syzbot code.

--=20
Aleksandr

On Tue, Nov 21, 2023 at 10:45=E2=80=AFPM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> On Tue, Nov 21, 2023 at 01:13:15PM -0800, syzbot wrote:
> > This bug is marked as fixed by commit:
> > media: uvcvideo: Avoid cyclic entity chains due to malformed USB descri=
ptors
> >
> > But I can't find it in the tested trees[1] for more than 90 days.
> > Is it a correct commit? Please update it by replying:
> >
> > #syz fix: exact-commit-title
>
> What logic does syzbot use to try and find the commit upstream ? There's
> a commit with the exact same subject, what was missing to find it
> automatically ?
>
> > Until then the bug is still considered open and new crashes with
> > the same signature are ignored.
> >
> > Kernel: Linux
> > Dashboard link: https://syzkaller.appspot.com/bug?extid=3D0b0095300dfeb=
8a83dc8
> >
> > ---
> > [1] I expect the commit to be present in:
> >
> > 1. for-kernelci branch of
> > git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git
> >
> > 2. master branch of
> > git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git
> >
> > 3. master branch of
> > git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git
> >
> > 4. main branch of
> > git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git
> >
> > The full list of 9 trees can be found at
> > https://syzkaller.appspot.com/upstream/repos
>
> --
> Regards,
>
> Laurent Pinchart