Re: WARNING in check_corruption

Dmitry Vyukov
2019-10-21T08:47:08Z

On Fri, Oct 18, 2019 at 4:13 PM syzbot
<syzbot+2e88d23c0143e90d8303@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: 8ada228a Add linux-next specific files for 20191011
> git tree: linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=144265ab600000
> kernel config: https://syzkaller.appspot.com/x/.config?x=7cf4eed5fe42c31a
> dashboard link: https://syzkaller.appspot.com/bug?extid=2e88d23c0143e90d8303
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1249ad80e00000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13ca6de7600000

syzkaller managed to write to /dev/mem.
https://github.com/google/syzkaller/commit/ef4a2149feeadf5833638d9b6ec3e53cb8dfd39d
disables CONFIG_DEVMEM and CONFIG_DEVKMEM is syzbot config.

#syz invalid

> Bisection is inconclusive: the bug happens on the oldest tested release.
>
> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=158d26d7600000
> final crash: https://syzkaller.appspot.com/x/report.txt?x=178d26d7600000
> console output: https://syzkaller.appspot.com/x/log.txt?x=138d26d7600000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+2e88d23c0143e90d8303@syzkaller.appspotmail.com
>
> check: Corrupted low memory at 00000000b9a95c9f (2900 phys) = 000000e8
> ------------[ cut here ]------------
> Memory corruption detected in low memory
> WARNING: CPU: 0 PID: 3473 at arch/x86/kernel/check.c:161
> check_for_bios_corruption arch/x86/kernel/check.c:161 [inline]
> WARNING: CPU: 0 PID: 3473 at arch/x86/kernel/check.c:161
> check_corruption+0x159/0x1fc arch/x86/kernel/check.c:169
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 0 PID: 3473 Comm: kworker/0:2 Not tainted 5.4.0-rc2-next-20191011 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Workqueue: events check_corruption
> Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0x172/0x1f0 lib/dump_stack.c:113
> panic+0x2e3/0x75c kernel/panic.c:221
> __warn.cold+0x2f/0x35 kernel/panic.c:582
> report_bug+0x289/0x300 lib/bug.c:195
> fixup_bug arch/x86/kernel/traps.c:174 [inline]
> fixup_bug arch/x86/kernel/traps.c:169 [inline]
> do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267
> do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286
> invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028
> RIP: 0010:check_for_bios_corruption arch/x86/kernel/check.c:161 [inline]
> RIP: 0010:check_corruption+0x159/0x1fc arch/x86/kernel/check.c:169
> Code: 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d c3 80 3d 8b 00 90 08 00 75 a2
> 48 c7 c7 e0 6b a8 87 c6 05 7b 00 90 08 01 e8 af 0b 12 00 <0f> 0b eb 8b 48
> 89 df 89 55 d0 e8 88 45 7c 00 8b 55 d0 e9 4e ff ff
> RSP: 0018:ffff88809c8d7cf8 EFLAGS: 00010286
> RAX: 0000000000000000 RBX: ffff888000010000 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: ffffffff815cb3a6 RDI: ffffed101391af91
> RBP: ffff88809c8d7d30 R08: ffff88809c8e2080 R09: ffffed1015d06161
> R10: ffffed1015d06160 R11: ffff8880ae830b07 R12: ffff888000010000
> R13: 0000000000000001 R14: dffffc0000000000 R15: ffff888000000000
> process_one_work+0x9af/0x1740 kernel/workqueue.c:2269
> worker_thread+0x98/0xe40 kernel/workqueue.c:2415
> kthread+0x361/0x430 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 syzkaller@googlegroups.com.
>
> syzbot will keep track of this bug report. 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 bug, for details see:
> https://goo.gl/tpsmEJ#testing-patches
>
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