WARNING in check_corruption

[syzbot]

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

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@xxxxxxxxxxxxxxxxxxxxxxxxx

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..


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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