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From: Al Viro <viro@zeniv.linux.org.uk>
To: syzbot <syzbot+533f389d4026d86a2a95@syzkaller.appspotmail.com>
Cc: andrii@kernel.org, ast@kernel.org, axboe@kernel.dk,
	bpf@vger.kernel.org, cgroups@vger.kernel.org,
	christian.brauner@ubuntu.com, christian@brauner.io,
	daniel@iogearbox.net, dkadashev@gmail.com, hannes@cmpxchg.org,
	john.fastabend@gmail.com, kafai@fb.com, kpsingh@kernel.org,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	lizefan.x@bytedance.com, netdev@vger.kernel.org,
	songliubraving@fb.com, syzkaller-bugs@googlegroups.com,
	tj@kernel.org, torvalds@linux-foundation.org, yhs@fb.com
Subject: Re: [syzbot] general protection fault in percpu_ref_put
Date: Tue, 21 Sep 2021 06:23:17 +0000	[thread overview]
Message-ID: <YUl6VZhPHBqAx+6g@zeniv-ca.linux.org.uk> (raw)
In-Reply-To: <000000000000f8be2b05cc788686@google.com>

On Mon, Sep 20, 2021 at 07:55:16PM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    4357f03d6611 Merge tag 'pm-5.15-rc2' of git://git.kernel.o..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=173e2d27300000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=ccfb8533b1cbe3b1
> dashboard link: https://syzkaller.appspot.com/bug?extid=533f389d4026d86a2a95
> compiler:       Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1395c6f1300000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11568cad300000
> 
> The issue was bisected to:
> 
> commit 020250f31c4c75ac7687a673e29c00786582a5f4
> Author: Dmitry Kadashev <dkadashev@gmail.com>
> Date:   Thu Jul 8 06:34:43 2021 +0000
> 
>     namei: make do_linkat() take struct filename
> 
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=137e8a4b300000
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=10fe8a4b300000
> console output: https://syzkaller.appspot.com/x/log.txt?x=177e8a4b300000

I would be very surprised if that was true.  After the first step of bisect
you've traded one oops for another, and *that* went to do_linkat() breakage.
Which should be fixed by fdfc346302a7.

Look at the oopsen - initial and final ones look very different.

      reply	other threads:[~2021-09-21  6:23 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-21  2:55 [syzbot] general protection fault in percpu_ref_put syzbot
2021-09-21  6:23 ` Al Viro [this message]

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