Subject: WARNING in smc_unhash_sk

From: syzbot <[email-masked]>
Date: Fri, 23 Feb 2018 07:59:01 -0800

Hello,

syzbot hit the following crash on upstream commit
af3e79d29555b97dd096e2f8e36a0f50213808a8 (Tue Feb 20 18:05:02 2018 +0000)
Merge tag 'leds_for-4.16-rc3' of  
git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds

So far this crash happened 27 times on  
https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/master,  
net-next, upstream.
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: [email-masked]
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WARNING: CPU: 1 PID: 9921 at ./include/net/sock.h:638 sk_del_node_init  
include/net/sock.h:638 [inline]
WARNING: CPU: 1 PID: 9921 at ./include/net/sock.h:638  
smc_unhash_sk+0x335/0x450 net/smc/af_smc.c:90
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 9921 Comm: syzkaller089677 Not tainted 4.16.0-rc2+ #324
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:17 [inline]
  dump_stack+0x194/0x24d lib/dump_stack.c:53
  panic+0x1e4/0x41c kernel/panic.c:183
  __warn+0x1dc/0x200 kernel/panic.c:547
  report_bug+0x211/0x2d0 lib/bug.c:184
  fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:178
  fixup_bug arch/x86/kernel/traps.c:247 [inline]
  do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
  invalid_op+0x58/0x80 arch/x86/entry/entry_64.S:957
RIP: 0010:sk_del_node_init include/net/sock.h:638 [inline]
RIP: 0010:smc_unhash_sk+0x335/0x450 net/smc/af_smc.c:90
RSP: 0018:ffff8801b639f198 EFLAGS: 00010293
RAX: ffff8801b684a340 RBX: 1ffff10036c73e37 RCX: ffffffff85a3f1f5
RDX: 0000000000000000 RSI: dffffc0000000000 RDI: 1ffff10036c73e3b
RBP: ffff8801b639f280 R08: dffffc0000000000 R09: 0000000000000004
R10: ffff8801b639f050 R11: 0000000000000004 R12: ffff8801b639f258
R13: ffffffff87669b40 R14: ffff8801c08d57c0 R15: 1ffff10036c73e3b
  smc_release+0x321/0x580 net/smc/af_smc.c:148
  sock_release+0x8d/0x1e0 net/socket.c:595
  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
  get_signal+0x73a/0x16d0 kernel/signal.c:2469
  do_signal+0x90/0x1e90 arch/x86/kernel/signal.c:809
  exit_to_usermode_loop+0x258/0x2f0 arch/x86/entry/common.c:162
  prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
  syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
  do_syscall_64+0x6e5/0x940 arch/x86/entry/common.c:292
  entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x44cad9
RSP: 002b:00007fbf24687ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000007
RAX: 0000000000000001 RBX: 0000000000700024 RCX: 000000000044cad9
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000020000080
RBP: 0000000000700020 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000080ef3f R14: 00007fbf246889c0 R15: 0000000000000005
Dumping ftrace buffer:
    (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..

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