WARNING: locking bug in selinux_netlbl_socket_connect

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: f97c81dc Merge tag 'armsoc-late' of git://git.kernel.org/p..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=127b709d600000
kernel config: https://syzkaller.appspot.com/x/.config?x=10283c2b00ab4cd7
dashboard link: https://syzkaller.appspot.com/bug?extid=5fa07e4e18e4eb1ccb12
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12996841600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+5fa07e...@syzkaller.appspotmail.com

WARNING: CPU: 0 PID: 10315 at kernel/locking/lockdep.c:840
look_up_lock_class kernel/locking/lockdep.c:840 [inline]
WARNING: CPU: 0 PID: 10315 at kernel/locking/lockdep.c:840
register_lock_class+0x206/0x1850 kernel/locking/lockdep.c:1185
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 10315 Comm: syz-executor.0 Not tainted 5.3.0+ #0
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+0x2dc/0x755 kernel/panic.c:219
__warn.cold+0x20/0x4c kernel/panic.c:576
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+0x23/0x30 arch/x86/entry/entry_64.S:1028
RIP: 0010:look_up_lock_class kernel/locking/lockdep.c:840 [inline]
RIP: 0010:register_lock_class+0x206/0x1850 kernel/locking/lockdep.c:1185
Code: fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 aa 10 00 00 4c 3b 7b
18 44 8b 35 d5 de 55 09 74 0b 48 81 3b a0 65 06 8a 74 02 <0f> 0b 45 85 ed
0f 84 71 03 00 00 f6 85 70 ff ff ff 01 0f 85 64 03
RSP: 0018:ffff888096777a48 EFLAGS: 00010002
RAX: dffffc0000000000 RBX: ffff888093ff78e0 RCX: 0000000000000000
RDX: 1ffff110127fef1f RSI: 0000000000000000 RDI: ffff888093ff78f8
RBP: ffff888096777b10 R08: 1ffff11012ceef51 R09: ffffffff8aaea0e0
R10: ffffffff8a7753c8 R11: 0000000000000000 R12: ffffffff8a7b5d20
R13: 0000000000000000 R14: 0000000000000000 R15: ffffffff884766e0
__lock_acquire+0xf4/0x4e70 kernel/locking/lockdep.c:3837
lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x33/0x50 kernel/locking/spinlock.c:175
spin_lock_bh include/linux/spinlock.h:343 [inline]
lock_sock_nested+0x41/0x120 net/core/sock.c:2929
lock_sock include/net/sock.h:1522 [inline]
selinux_netlbl_socket_connect+0x20/0xc0 security/selinux/netlabel.c:607
selinux_socket_connect+0x6a/0x90 security/selinux/hooks.c:4745
security_socket_connect+0x77/0xc0 security/security.c:1958
__sys_connect+0x19d/0x330 net/socket.c:1824
__do_sys_connect net/socket.c:1839 [inline]
__se_sys_connect net/socket.c:1836 [inline]
__x64_sys_connect+0x73/0xb0 net/socket.c:1836
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459a09
Code: fd b7 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fc302ec5c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459a09
RDX: 000000000000001c RSI: 0000000020000080 RDI: 0000000000000005
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fc302ec66d4
R13: 00000000004bff42 R14: 00000000004d1eb0 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

[Paul Moore]

This doesn't appear to be related to selinux_netlbl_socket_connect();
I believe it should be okay to call lock_sock() in that context.

--
paul moore
www.paul-moore.com

[Dmitry Vyukov]

FTR, this is this warning:

static inline struct lock_class *
look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)
{
....
/*
* Huh! same key, different name? Did someone trample
* on some memory? We're most confused.
*/
WARN_ON_ONCE(class->name != lock->name &&
lock->key != &__lockdep_no_validate__);


So something fishy happens here (stack overflow again?).

[Paul Moore]

Yeah, when I saw that yesterday I figured it was something beyond the
usual connect() call path; something else is going on I think. I
didn't see a reproducer for this, is that right?

--
paul moore
www.paul-moore.com

[Eric Biggers]

There was a link to a syzkaller reproducer in the original email.

- Eric

[Paul Moore]

Heh, I had to re-read that original report a half-dozen times, I kept
reading "repro" as "repo" :)

--
paul moore
www.paul-moore.com

[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.