BUG: corrupted list in tipc_nametbl_unsubscribe

[syzbot]

Hello,

syzbot hit the following crash on net-next commit
fd372a7a9e5e9d8011a0222d10edd3523abcd3b1 (Thu Mar 8 19:43:48 2018 +0000)
Merge tag 'mlx5-updates-2018-02-28-2' of
git://git.kernel.org/pub/scm/linux/kernel/git/mellanox/linux

So far this crash happened 2 times on net-next.
C reproducer is attached.
syzkaller reproducer is attached.
Raw console output is attached.
compiler: gcc (GCC) 7.1.1 20170620
.config is attached.

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Reported-by: syzbot+f25098...@syzkaller.appspotmail.com
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R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000
Name sequence creation failed, no memory
Failed to create subscription for {1020,0,4294967295}
list_del corruption. prev->next should be 00000000f6eff561, but
was (null)
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:53!
invalid opcode: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
(ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 4187 Comm: syzkaller951783 Not tainted 4.16.0-rc4+ #258
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:__list_del_entry_valid+0xef/0x150 lib/list_debug.c:51
RSP: 0018:ffff8801b7ed6ec8 EFLAGS: 00010282
RAX: 0000000000000054 RBX: ffffffff879ffd20 RCX: 0000000000000000
RDX: 0000000000000054 RSI: 1ffff10036fdad8e RDI: ffffed0036fdadcd
RBP: ffff8801b7ed6ee0 R08: 1ffff10036fdad25 R09: 0000000000000000
R10: ffff8801b7ed6da8 R11: 0000000000000000 R12: ffffffffffffffff
R13: ffff8801b7ed7080 R14: ffff8801b7f6d998 R15: ffff8801d59c6c00
FS: 0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3357e55000 CR3: 0000000006e22001 CR4: 00000000001606f0
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_init include/linux/list.h:159 [inline]
tipc_nametbl_unsubscribe+0x337/0x990 net/tipc/name_table.c:855
tipc_sub_unsubscribe+0x6d/0x2e0 net/tipc/subscr.c:164
tipc_conn_delete_sub+0x324/0x4a0 net/tipc/topsrv.c:245
tipc_topsrv_kern_unsubscr+0x21d/0x350 net/tipc/topsrv.c:598
tipc_group_delete+0x2c0/0x3d0 net/tipc/group.c:231
tipc_sk_leave+0x10b/0x200 net/tipc/socket.c:2794
tipc_release+0x154/0xff0 net/tipc/socket.c:577
sock_release+0x8d/0x1e0 net/socket.c:594
sock_close+0x16/0x20 net/socket.c:1149
__fput+0x327/0x7e0 fs/file_table.c:209
____fput+0x15/0x20 fs/file_table.c:243
task_work_run+0x199/0x270 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0x9bb/0x1ad0 kernel/exit.c:865
do_group_exit+0x149/0x400 kernel/exit.c:968
SYSC_exit_group kernel/exit.c:979 [inline]
SyS_exit_group+0x1d/0x20 kernel/exit.c:977
do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x43f0c8
RSP: 002b:00007ffd4b6bf148 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043f0c8
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00000000004bf1a8 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 0000000020265000 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000006d1180 R14: 0000000000000000 R15: 0000000000000000
Code: 4c 89 e2 48 c7 c7 c0 7c 40 86 e8 75 f6 fb fe 0f 0b 48 c7 c7 20 7d 40
86 e8 67 f6 fb fe 0f 0b 48 c7 c7 80 7d 40 86 e8 59 f6 fb fe <0f> 0b 48 c7
c7 e0 7d 40 86 e8 4b f6 fb fe 0f 0b 48 89 df 48 89
RIP: __list_del_entry_valid+0xef/0x150 lib/list_debug.c:51 RSP:
ffff8801b7ed6ec8
---[ end trace 1d4e489a074c9174 ]---


---
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[Eric Biggers]

This was fixed by commit c3317f4db831b75 (thanks Jon!):

#syz fix: tipc: fix unbalanced reference counter

- Eric