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From:   Eric Dumazet <edumazet@google.com>
Date:   Wed, 5 Jan 2022 07:42:10 -0800
Message-ID: <CANn89iK3tP3rANSWM7_=imMeMcUknT0U2GyfA9W4v12ad6_PkQ@mail.gmail.com>
Subject: Re: [syzbot] WARNING in signalfd_cleanup
To:     syzbot <syzbot+5426c7ed6868c705ca14@syzkaller.appspotmail.com>
Cc:     changbin.du@intel.com, Daniel Borkmann <daniel@iogearbox.net>,
        David Miller <davem@davemloft.net>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Jakub Kicinski <kuba@kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Yajun Deng <yajun.deng@linux.dev>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Wed, Jan 5, 2022 at 7:37 AM syzbot
<syzbot+5426c7ed6868c705ca14@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    6b8d4927540e Add linux-next specific files for 20220104
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=159d88e3b00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=45c9bbbf2ae8e3d3
> dashboard link: https://syzkaller.appspot.com/bug?extid=5426c7ed6868c705ca14
> 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=117be65db00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15a75c8db00000
>

C repro looks legit, point to an io_uring issue.

> The issue was bisected to:

Please ignore the bisection.

>
> commit e4b8954074f6d0db01c8c97d338a67f9389c042f
> Author: Eric Dumazet <edumazet@google.com>
> Date:   Tue Dec 7 01:30:37 2021 +0000
>
>     netlink: add net device refcount tracker to struct ethnl_req_info
>
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=12bca4e3b00000
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=11bca4e3b00000
> console output: https://syzkaller.appspot.com/x/log.txt?x=16bca4e3b00000
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+5426c7ed6868c705ca14@syzkaller.appspotmail.com
> Fixes: e4b8954074f6 ("netlink: add net device refcount tracker to struct ethnl_req_info")
>
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 3604 at kernel/sched/wait.c:245 __wake_up_pollfree+0x40/0x50 kernel/sched/wait.c:246
> Modules linked in:
> CPU: 0 PID: 3604 Comm: syz-executor714 Not tainted 5.16.0-rc8-next-20220104-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:__wake_up_pollfree+0x40/0x50 kernel/sched/wait.c:245
> Code: f3 ff ff 48 8d 6b 40 48 b8 00 00 00 00 00 fc ff df 48 89 ea 48 c1 ea 03 80 3c 02 00 75 11 48 8b 43 40 48 39 c5 75 03 5b 5d c3 <0f> 0b 5b 5d c3 48 89 ef e8 13 d8 69 00 eb e5 cc 48 c1 e7 06 48 63
> RSP: 0018:ffffc90001aaf9f8 EFLAGS: 00010083
> RAX: ffff88801cd623f0 RBX: ffff88801bec8048 RCX: 0000000000000000
> RDX: 1ffff110037d9011 RSI: 0000000000000004 RDI: 0000000000000001
> RBP: ffff88801bec8088 R08: 0000000000000000 R09: ffff88801bec804b
> R10: ffffed10037d9009 R11: 0000000000000000 R12: ffff88801bec8040
> R13: ffff88801e029d40 R14: dffffc0000000000 R15: ffff88807eb50000
> FS:  00005555573ad300(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000200000c0 CR3: 000000001e5e4000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  wake_up_pollfree include/linux/wait.h:271 [inline]
>  signalfd_cleanup+0x42/0x60 fs/signalfd.c:38
>  __cleanup_sighand kernel/fork.c:1596 [inline]
>  __cleanup_sighand+0x72/0xb0 kernel/fork.c:1593
>  __exit_signal kernel/exit.c:159 [inline]
>  release_task+0xc02/0x17e0 kernel/exit.c:200
>  wait_task_zombie kernel/exit.c:1117 [inline]
>  wait_consider_task+0x2fa6/0x3b80 kernel/exit.c:1344
>  do_wait_thread kernel/exit.c:1407 [inline]
>  do_wait+0x6ca/0xce0 kernel/exit.c:1524
>  kernel_wait4+0x14c/0x260 kernel/exit.c:1687
>  __do_sys_wait4+0x13f/0x150 kernel/exit.c:1715
>  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: 0033:0x7facd6682386
> Code: 0f 1f 40 00 31 c9 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 49 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 11 b8 3d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 90 48 83 ec 28 89 54 24 14 48 89 74 24
> RSP: 002b:00007ffdb91adef8 EFLAGS: 00000246 ORIG_RAX: 000000000000003d
> RAX: ffffffffffffffda RBX: 000000000000c646 RCX: 00007facd6682386
> RDX: 0000000040000001 RSI: 00007ffdb91adf14 RDI: 00000000ffffffff
> RBP: 0000000000000f17 R08: 0000000000000032 R09: 00007ffdb91ec080
> R10: 0000000000000000 R11: 0000000000000246 R12: 431bde82d7b634db
> R13: 00007ffdb91adf14 R14: 0000000000000000 R15: 0000000000000000
>  </TASK>
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> syzbot can test patches for this issue, for details see:
> https://goo.gl/tpsmEJ#testing-patches