BUG: corrupted list in freeary

[syzbot <syzbot+c92d3646e35bc5d1a909@syzkaller.appspotmail.com>]

Hello,

syzbot found the following crash on:

HEAD commit:    e195ca6cb6f2 Merge branch 'for-linus' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10d3e6a3400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=73e2bc0cb6463446
dashboard link: https://syzkaller.appspot.com/bug?extid=c92d3646e35bc5d1a909
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+c92d3646e35bc5d1a909@syzkaller.appspotmail.com

input: syz1 as /devices/virtual/input/input670
input: syz1 as /devices/virtual/input/input671
list_del corruption. prev->next should be ffff8881dae2cdb8, but was  
0000000000100000
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:53!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 6194 Comm: syz-executor5 Not tainted 4.20.0-rc3+ #348
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:__list_del_entry_valid.cold.1+0x48/0x4a lib/list_debug.c:51
Code: d0 60 88 e8 b2 31 d2 fd 0f 0b 48 89 de 48 c7 c7 00 d2 60 88 e8 a1 31  
d2 fd 0f 0b 48 89 de 48 c7 c7 a0 d1 60 88 e8 90 31 d2 fd <0f> 0b 48 89 d9  
48 c7 c7 60 d2 60 88 e8 7f 31 d2 fd 0f 0b 48 89 f1
RSP: 0018:ffff8881848fee80 EFLAGS: 00010286
RAX: 0000000000000054 RBX: ffff8881dae2cdb8 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8165eaf5 RDI: 0000000000000005
RBP: ffff8881848fee98 R08: ffff8881848f26c0 R09: 0000000000000006
R10: 0000000000000000 R11: ffff8881848f26c0 R12: ffff8881c3173a00
R13: ffff8881be118118 R14: ffff8881848ff280 R15: dffffc0000000000
FS:  00000000020b2940(0000) GS:ffff8881dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000625208 CR3: 00000001c10d3000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  __list_del_entry include/linux/list.h:117 [inline]
  list_del include/linux/list.h:125 [inline]
  unlink_queue ipc/sem.c:786 [inline]
  freeary+0xbd1/0x1a40 ipc/sem.c:1160
  free_ipcs+0x9f/0x1c0 ipc/namespace.c:112
  sem_exit_ns+0x20/0x40 ipc/sem.c:237
  free_ipc_ns ipc/namespace.c:120 [inline]
  put_ipc_ns+0x66/0x180 ipc/namespace.c:152
  free_nsproxy+0xcf/0x220 kernel/nsproxy.c:180
  switch_task_namespaces+0xb3/0xd0 kernel/nsproxy.c:229
  exit_task_namespaces+0x17/0x20 kernel/nsproxy.c:234
  do_exit+0x1ad1/0x26d0 kernel/exit.c:866
  do_group_exit+0x177/0x440 kernel/exit.c:970
  get_signal+0x8b0/0x1980 kernel/signal.c:2517
  do_signal+0x9c/0x21c0 arch/x86/kernel/signal.c:816
  exit_to_usermode_loop+0x2e5/0x380 arch/x86/entry/common.c:162
  prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
  syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
  do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x410fa0
Code: 24 48 8b 4c 24 28 48 89 4c 24 08 88 44 24 10 c6 44 24 11 01 0f b6 44  
24 50 88 44 24 12 e8 18 15 01 00 48 8b 44 24 18 48 85 c0 <74> 59 48 89 44  
24 30 48 8b 48 18 48 8b 54 24 48 48 01 d1 48 89 88
RSP: 002b:00007fff19ab9c48 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: fffffffffffffe00 RBX: 0000000000000000 RCX: 0000000000410fa0
RDX: 0000000000000038 RSI: 0000000000728020 RDI: 00000000000000f9
RBP: 0000000000000003 R08: 0000000000006000 R09: 0000000000004000
R10: 00007fff19ab95e0 R11: 0000000000000246 R12: 0000000000000002
R13: 000000000008f53b R14: 00000000000002f8 R15: 0000000000000005
Modules linked in:
---[ end trace 9573c75ddafce7e3 ]---
RIP: 0010:__list_del_entry_valid.cold.1+0x48/0x4a lib/list_debug.c:51
Code: d0 60 88 e8 b2 31 d2 fd 0f 0b 48 89 de 48 c7 c7 00 d2 60 88 e8 a1 31  
d2 fd 0f 0b 48 89 de 48 c7 c7 a0 d1 60 88 e8 90 31 d2 fd <0f> 0b 48 89 d9  
48 c7 c7 60 d2 60 88 e8 7f 31 d2 fd 0f 0b 48 89 f1
RSP: 0018:ffff8881848fee80 EFLAGS: 00010286
RAX: 0000000000000054 RBX: ffff8881dae2cdb8 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8165eaf5 RDI: 0000000000000005
RBP: ffff8881848fee98 R08: ffff8881848f26c0 R09: 0000000000000006
R10: 0000000000000000 R11: ffff8881848f26c0 R12: ffff8881c3173a00
R13: ffff8881be118118 R14: ffff8881848ff280 R15: dffffc0000000000
FS:  00000000020b2940(0000) GS:ffff8881dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000625208 CR3: 00000001c10d3000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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