Subject: WARNING: locking bug in lock_sock_nested

From: syzbot <[email-masked]>
Date: Sun, 14 Apr 2019 04:29:05 -0700

Hello,

syzbot found the following crash on:

HEAD commit:    2d06b235 Merge tag 'for-5.1-rc4-tag' of git://git.kernel.o..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1521ba9f200000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4fb64439e07a1ec0
dashboard link: https://syzkaller.appspot.com/bug?extid=605a69fff339d9cc221e
compiler:       gcc (GCC) 9.0.0 20181231 (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: [email-masked]

WARNING: CPU: 1 PID: 24536 at kernel/locking/lockdep.c:746  
arch_local_save_flags arch/x86/include/asm/paravirt.h:762 [inline]
WARNING: CPU: 1 PID: 24536 at kernel/locking/lockdep.c:746  
arch_local_save_flags arch/x86/include/asm/paravirt.h:760 [inline]
WARNING: CPU: 1 PID: 24536 at kernel/locking/lockdep.c:746  
look_up_lock_class kernel/locking/lockdep.c:737 [inline]
WARNING: CPU: 1 PID: 24536 at kernel/locking/lockdep.c:746  
register_lock_class+0xe10/0x1860 kernel/locking/lockdep.c:1090
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 24536 Comm: syz-executor.5 Not tainted 5.1.0-rc4+ #63
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x172/0x1f0 lib/dump_stack.c:113
  panic+0x2cb/0x65c kernel/panic.c:214
  __warn.cold+0x20/0x45 kernel/panic.c:571
  report_bug+0x263/0x2b0 lib/bug.c:186
  fixup_bug arch/x86/kernel/traps.c:179 [inline]
  fixup_bug arch/x86/kernel/traps.c:174 [inline]
  do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272
  do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291
  invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:973
RIP: 0010:look_up_lock_class kernel/locking/lockdep.c:746 [inline]
RIP: 0010:register_lock_class+0xe10/0x1860 kernel/locking/lockdep.c:1090
Code: 00 48 89 da 4d 8b 76 c0 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80  
3c 02 00 0f 85 23 07 00 00 4c 89 33 e9 e3 f4 ff ff 0f 0b <0f> 0b e9 ea f3  
ff ff 44 89 e0 4c 8b 95 50 ff ff ff 83 c0 01 4c 8b
RSP: 0018:ffff88808a40f5e0 EFLAGS: 00010083
RAX: dffffc0000000000 RBX: ffff8880908061e0 RCX: 0000000000000000
RDX: 1ffff11012100c3f RSI: 0000000000000000 RDI: ffff8880908061f8
RBP: ffff88808a40f6a8 R08: 1ffff11011481ec4 R09: ffffffff8a5c8a20
R10: ffffffff8a0afe30 R11: 0000000000000000 R12: ffffffff8a11dec0
R13: 0000000000000000 R14: 0000000000000000 R15: ffffffff87fb8da0
  __lock_acquire+0xf9/0x3fb0 kernel/locking/lockdep.c:3582
  lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211
  __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
  _raw_spin_lock_bh+0x33/0x50 kernel/locking/spinlock.c:168
  spin_lock_bh include/linux/spinlock.h:334 [inline]
  lock_sock_nested+0x41/0x120 net/core/sock.c:2912
  lock_sock include/net/sock.h:1513 [inline]
  do_ipv6_setsockopt.isra.0+0x27e/0x49e0 net/ipv6/ipv6_sockglue.c:167
  ipv6_setsockopt+0xfc/0x170 net/ipv6/ipv6_sockglue.c:946
  udpv6_setsockopt+0x68/0xb0 net/ipv6/udp.c:1570
  sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3120
  __sys_setsockopt+0x180/0x280 net/socket.c:2046
  __do_sys_setsockopt net/socket.c:2057 [inline]
  __se_sys_setsockopt net/socket.c:2054 [inline]
  __x64_sys_setsockopt+0xbe/0x150 net/socket.c:2054
  do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458c29
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fe15476fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000458c29
RDX: 0000000000000023 RSI: 0000000000000029 RDI: 0000000000000006
RBP: 000000000073bfa0 R08: 00000000000000e8 R09: 0000000000000000
R10: 00000000200001c0 R11: 0000000000000246 R12: 00007fe1547706d4
R13: 00000000004cd398 R14: 00000000004db3f8 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..

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