Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: KASAN: use-after-free Read in percpu_ref_switch_to_atomic_rcu
To:     Dmitry Vyukov <dvyukov@google.com>,
        syzbot <syzbot+e017e49c39ab484ac87a@syzkaller.appspotmail.com>,
        Al Viro <viro@zeniv.linux.org.uk>, io-uring@vger.kernel.org,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>
Cc:     Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        Thomas Gleixner <tglx@linutronix.de>, tony.luck@intel.com,
        the arch/x86 maintainers <x86@kernel.org>
References: <00000000000067c6df059df7f9f5@google.com>
 <CACT4Y+ZVLs7O84qixsvFqk_Nur1WOaCU81RiCwDf3wOqvHB-ag@mail.gmail.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <3f805e51-1db7-3e57-c9a3-15a20699ea54@kernel.dk>
Date:   Wed, 4 Mar 2020 07:40:02 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.4.1
MIME-Version: 1.0
In-Reply-To: <CACT4Y+ZVLs7O84qixsvFqk_Nur1WOaCU81RiCwDf3wOqvHB-ag@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 3/4/20 12:59 AM, Dmitry Vyukov wrote:
> On Fri, Feb 7, 2020 at 9:14 AM syzbot
> <syzbot+e017e49c39ab484ac87a@syzkaller.appspotmail.com> wrote:
>>
>> Hello,
>>
>> syzbot found the following crash on:
>>
>> HEAD commit:    4c7d00cc Merge tag 'pwm/for-5.6-rc1' of git://git.kernel.o..
>> git tree:       upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=12fec785e00000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=e162021ddededa72
>> dashboard link: https://syzkaller.appspot.com/bug?extid=e017e49c39ab484ac87a
>> compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
>>
>> Unfortunately, I don't have any reproducer for this crash yet.
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+e017e49c39ab484ac87a@syzkaller.appspotmail.com
> 
> +io_uring maintainers
> 
> Here is a repro:
> https://gist.githubusercontent.com/dvyukov/6b340beab6483a036f4186e7378882ce/raw/cd1922185516453c201df8eded1d4b006a6d6a3a/gistfile1.txt

I've queued up a fix for this:

https://git.kernel.dk/cgit/linux-block/commit/?h=io_uring-5.6&id=9875fe3dc4b8cff1f1b440fb925054a5124403c3

-- 
Jens Axboe