From: Jens Axboe <axboe@kernel.dk>
To: syzbot <syzbot+fd15ff734dace9e16437@syzkaller.appspotmail.com>,
bcrl@kvack.org, hch@lst.de, linux-aio@kvack.org,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
ming.lei@redhat.com, syzkaller-bugs@googlegroups.com,
tj@kernel.org, viro@zeniv.linux.org.uk, vkabatov@redhat.com
Subject: Re: general protection fault in percpu_ref_exit
Date: Thu, 8 Oct 2020 19:23:02 -0600 [thread overview]
Message-ID: <165db20c-bfc5-fca8-1ecf-45d85ea5d9e2@kernel.dk> (raw)
In-Reply-To: <000000000000b1412b05b12eab0a@google.com>
On 10/8/20 2:28 PM, syzbot wrote:
> syzbot has bisected this issue to:
>
> commit 2b0d3d3e4fcfb19d10f9a82910b8f0f05c56ee3e
> Author: Ming Lei <ming.lei@redhat.com>
> Date: Thu Oct 1 15:48:41 2020 +0000
>
> percpu_ref: reduce memory footprint of percpu_ref in fast path
>
> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=126930d0500000
> start commit: 8b787da7 Add linux-next specific files for 20201007
> git tree: linux-next
> final oops: https://syzkaller.appspot.com/x/report.txt?x=116930d0500000
> console output: https://syzkaller.appspot.com/x/log.txt?x=166930d0500000
> kernel config: https://syzkaller.appspot.com/x/.config?x=aac055e9c8fbd2b8
> dashboard link: https://syzkaller.appspot.com/bug?extid=fd15ff734dace9e16437
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=119a0568500000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=106c0a8b900000
>
> Reported-by: syzbot+fd15ff734dace9e16437@syzkaller.appspotmail.com
> Fixes: 2b0d3d3e4fcf ("percpu_ref: reduce memory footprint of percpu_ref in fast path")
>
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
Ming, this looks like a call of percpu_ref_exit() on a zeroed refs (that
hasn't been initialized). Really a caller error imho, but might make sense
to be a bit safer there.
--
Jens Axboe
next prev parent reply other threads:[~2020-10-09 1:23 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-08 15:09 general protection fault in percpu_ref_exit syzbot
2020-10-08 20:28 ` syzbot
2020-10-09 1:23 ` Jens Axboe [this message]
2020-10-09 4:05 ` Ming Lei
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