BUG: unable to handle kernel paging request in memcmp

[syzbot]

Hello,

syzkaller hit the following crash on
6084b576dca2e898f5c101baef151f7bfdbb606d
git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.

Unfortunately, I don't have any reproducer for this bug yet.


BUG: unable to handle kernel paging request at ffffffffffffffd8
IP: memcmp+0x9/0x40 lib/string.c:860
PGD 3021067 P4D 3021067 PUD 3023067 PMD 0
Oops: 0000 [#1] SMP
Dumping ftrace buffer:
(ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 18580 Comm: syz-executor3 Not tainted 4.15.0-rc3-next-20171214+
#67
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:memcmp+0x9/0x40 lib/string.c:860
RSP: 0018:ffffc90000f13ea0 EFLAGS: 00010202
RAX: 0000000000000000 RBX: ffffffffffffffd8 RCX: 0000000000000004
RDX: 0000000000000004 RSI: ffffc90000f13eec RDI: ffffffffffffffd8
RBP: ffffc90000f13ea0 R08: 0000000000000001 R09: 0000000000000002
R10: ffffc90000f13e38 R11: 0000000000000002 R12: ffff8801fd3109f0
R13: ffffc90000f13f28 R14: ffff8801fd2dec00 R15: 0000000000000068
FS: 00007fd1a2fd1700(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd8 CR3: 00000001ffb69003 CR4: 00000000001626f0
Call Trace:
memcmp include/linux/string.h:385 [inline]
rhashtable_compare include/linux/rhashtable.h:612 [inline]
__rhashtable_lookup include/linux/rhashtable.h:634 [inline]
rhashtable_lookup include/linux/rhashtable.h:666 [inline]
rhashtable_lookup_fast include/linux/rhashtable.h:692 [inline]
ipc_findkey ipc/util.c:183 [inline]
ipcget_public ipc/util.c:378 [inline]
ipcget+0x1a2/0x620 ipc/util.c:654
SYSC_msgget ipc/msg.c:280 [inline]
SyS_msgget+0x48/0x60 ipc/msg.c:266
entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452a09
RSP: 002b:00007fd1a2fd0c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000044
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452a09
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 00000000798e7462
RBP: 00000000000003f2 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f2f50
R13: 00000000ffffffff R14: 00007fd1a2fd16d4 R15: 0000000000000000
Code: 74 1a 48 01 fa 48 89 f8 eb 07 0f b6 08 39 f1 74 09 48 83 c0 01 48 39
d0 75 f0 5d c3 48 89 f8 5d c3 90 55 48 85 d2 48 89 e5 74 2e <0f> b6 07 0f
b6 0e 29 c8 75 1e 48 01 fa eb 0c 0f b6 0f 44 0f b6
RIP: memcmp+0x9/0x40 lib/string.c:860 RSP: ffffc90000f13ea0
CR2: ffffffffffffffd8
---[ end trace a28e6436c6f945bb ]---
Kernel panic - not syncing: Fatal exception
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[Dmitry Vyukov]

old bug bankruptcy

#syz invalid

On Tue, Dec 19, 2017 at 1:28 PM, syzbot
<bot+fff9a11c8fc9c9f9d0...@syzkaller.appspotmail.com>
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