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Date:   Mon, 9 May 2022 11:02:41 -0600
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Subject: Re: [syzbot] KASAN: use-after-free Read in bio_poll
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To:     syzbot <syzbot+99938118dfd9e1b0741a@syzkaller.appspotmail.com>,
        andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org,
        daniel@iogearbox.net, john.fastabend@gmail.com, kafai@fb.com,
        kpsingh@kernel.org, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        songliubraving@fb.com, syzkaller-bugs@googlegroups.com, yhs@fb.com,
        Ming Lei <ming.lei@redhat.com>, Christoph Hellwig <hch@lst.de>
References: <00000000000029572505de968021@google.com>
From:   Jens Axboe <axboe@kernel.dk>
In-Reply-To: <00000000000029572505de968021@google.com>
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On 5/9/22 10:14 AM, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    c5eb0a61238d Linux 5.18-rc6
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=112bf03ef00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=79caa0035f59d385
> dashboard link: https://syzkaller.appspot.com/bug?extid=99938118dfd9e1b0741a
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12311571f00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=177a2e86f00000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+99938118dfd9e1b0741a@syzkaller.appspotmail.com
> 
> ==================================================================
> BUG: KASAN: use-after-free in bio_poll+0x275/0x3c0 block/blk-core.c:942
> Read of size 4 at addr ffff8880751d92b4 by task syz-executor486/3607
> 
> CPU: 0 PID: 3607 Comm: syz-executor486 Not tainted 5.18.0-rc6-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
>  print_address_description.constprop.0.cold+0xeb/0x495 mm/kasan/report.c:313
>  print_report mm/kasan/report.c:429 [inline]
>  kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491
>  bio_poll+0x275/0x3c0 block/blk-core.c:942
>  __iomap_dio_rw+0x10ee/0x1ae0 fs/iomap/direct-io.c:658
>  iomap_dio_rw+0x38/0x90 fs/iomap/direct-io.c:681
>  ext4_dio_write_iter fs/ext4/file.c:566 [inline]
>  ext4_file_write_iter+0xe4d/0x1510 fs/ext4/file.c:677
>  call_write_iter include/linux/fs.h:2050 [inline]
>  do_iter_readv_writev+0x3d1/0x640 fs/read_write.c:726
>  do_iter_write+0x182/0x700 fs/read_write.c:852
>  vfs_writev+0x1aa/0x630 fs/read_write.c:925
>  do_pwritev+0x1b6/0x270 fs/read_write.c:1022
>  __do_sys_pwritev2 fs/read_write.c:1081 [inline]
>  __se_sys_pwritev2 fs/read_write.c:1072 [inline]
>  __x64_sys_pwritev2+0xeb/0x150 fs/read_write.c:1072
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7f6846af7e69

Guys, should we just queue:

ommit 9650b453a3d4b1b8ed4ea8bcb9b40109608d1faf
Author: Ming Lei <ming.lei@redhat.com>
Date:   Wed Apr 20 22:31:10 2022 +0800

    block: ignore RWF_HIPRI hint for sync dio

up for 5.18 and stable?

-- 
Jens Axboe