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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Wed, 16 Sep 2020 06:55:09 +0200
Message-ID: <CACT4Y+bvwOZCF_--T=_Vxk1YCqGxMGEyrs3tRSyGNw1ENMJb1g@mail.gmail.com>
Subject: Re: WARNING in batadv_iv_send_outstanding_bat_ogm_packet
To:     Anant Thazhemadam <anant.thazhemadam@gmail.com>
Cc:     syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        syzkaller <syzkaller@googlegroups.com>,
        LKML <linux-kernel@vger.kernel.org>
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On Tue, Sep 15, 2020 at 8:34 PM Anant Thazhemadam
<anant.thazhemadam@gmail.com> wrote:
> On Monday, October 14, 2019 at 2:25:08 AM UTC+5:30 syzbot wrote:
>>
>> Hello,
>>
>> syzbot found the following crash on:
>>
>> HEAD commit: da940012 Merge tag 'char-misc-5.4-rc3' of git://git.kernel..
>> git tree: upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=13ffd808e00000
>> kernel config: https://syzkaller.appspot.com/x/.config?x=2d2fd92a28d3e50
>> dashboard link: https://syzkaller.appspot.com/bug?extid=c0b807de416427ff3dd1
>> compiler: clang version 9.0.0 (/home/glider/llvm/clang
>> 80fee25776c2fb61e74c1ecb1a523375c2500b69)
>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=141ffd77600000
>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11edd580e00000
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+c0b807...@syzkaller.appspotmail.com
>>
>> ------------[ cut here ]------------
>> WARNING: CPU: 1 PID: 30 at net/batman-adv/bat_iv_ogm.c:382
>> batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:382 [inline]
>> WARNING: CPU: 1 PID: 30 at net/batman-adv/bat_iv_ogm.c:382
>> batadv_iv_send_outstanding_bat_ogm_packet+0x6b4/0x770
>> net/batman-adv/bat_iv_ogm.c:1663
>> Kernel panic - not syncing: panic_on_warn set ...
>> CPU: 1 PID: 30 Comm: kworker/u4:2 Not tainted 5.4.0-rc2+ #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>> Google 01/01/2011
>> Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
>> Call Trace:
>> __dump_stack lib/dump_stack.c:77 [inline]
>> dump_stack+0x1d8/0x2f8 lib/dump_stack.c:113
>> panic+0x264/0x7a9 kernel/panic.c:221
>> __warn+0x20e/0x210 kernel/panic.c:582
>> report_bug+0x1b6/0x2f0 lib/bug.c:195
>> fixup_bug arch/x86/kernel/traps.c:179 [inline]
>> do_error_trap+0xd7/0x440 arch/x86/kernel/traps.c:272
>> do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:291
>> invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028
>> RIP: 0010:batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:382 [inline]
>> RIP: 0010:batadv_iv_send_outstanding_bat_ogm_packet+0x6b4/0x770
>> net/batman-adv/bat_iv_ogm.c:1663
>> Code: 66 05 00 eb 05 e8 9c 48 23 fa 48 83 c4 68 5b 41 5c 41 5d 41 5e 41 5f
>> 5d c3 e8 88 48 23 fa 0f 0b e9 34 ff ff ff e8 7c 48 23 fa <0f> 0b e9 28 ff
>> ff ff 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c c1 f9 ff
>> RSP: 0018:ffff8880a9abfc48 EFLAGS: 00010293
>> RAX: ffffffff874fe8a4 RBX: ffff888094160870 RCX: ffff8880a9ab2080
>> RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
>> RBP: ffff8880a9abfcd8 R08: ffffffff874fe28e R09: ffffed10123e6969
>> R10: ffffed10123e6969 R11: 0000000000000000 R12: ffff888091f34000
>> R13: dffffc0000000000 R14: ffff8880a80c5000 R15: ffff8880a4481400
>> process_one_work+0x7ef/0x10e0 kernel/workqueue.c:2269
>> worker_thread+0xc01/0x1630 kernel/workqueue.c:2415
>> kthread+0x332/0x350 kernel/kthread.c:255
>> ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
>> Kernel Offset: disabled
>> Rebooting in 86400 seconds..
>>
>>
>> ---
>> This bug 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 syzk...@googlegroups.com.
>>
>> syzbot will keep track of this bug report. See:
>> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>> syzbot can test patches for this bug, for details see:
>> https://goo.gl/tpsmEJ#testing-patches
>
>
> For this bug, syzbot does not seem to be able to build the kernel anymore.
> Can bugs like these be considered and closed as invalid?
>
> Thanks,
> Anant

Hi Anant,

+syzkaler, lkml (nobody is generally reading syzkaller-bugs).

What do you mean by "not able to build a kernel for this bug"?
Building a kernel is not related to a particular bug. It's the same
for all bugs...