WARNING in aa_sock_msg_perm (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    31f4f5b4 Linux 5.4-rc7
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12887074e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=83de638b2a862933
dashboard link: https://syzkaller.appspot.com/bug?extid=e3b328542d4adc02a975
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: syzbot+e3b328542d4adc02a975@xxxxxxxxxxxxxxxxxxxxxxxxx

------------[ cut here ]------------
AppArmor WARN aa_sock_msg_perm: ((!sock)):
WARNING: CPU: 0 PID: 12781 at security/apparmor/lsm.c:920  
aa_sock_msg_perm.isra.0+0xdd/0x170 security/apparmor/lsm.c:920
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 12781 Comm: kworker/0:1 Not tainted 5.4.0-rc7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: krxrpcd rxrpc_peer_keepalive_worker
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x197/0x210 lib/dump_stack.c:118
 panic+0x2e3/0x75c kernel/panic.c:221
 __warn.cold+0x2f/0x35 kernel/panic.c:582
 report_bug+0x289/0x300 lib/bug.c:195
 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:aa_sock_msg_perm.isra.0+0xdd/0x170 security/apparmor/lsm.c:920
Code: 89 ef e8 26 e4 02 00 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 16 3a 60 fe  
48 c7 c6 e0 39 e1 87 48 c7 c7 e0 24 e1 87 e8 4b 6c 31 fe <0f> 0b e9 43 ff  
ff ff e8 f7 39 60 fe 48 c7 c6 e0 39 e1 87 48 c7 c7
RSP: 0018:ffff88809c3d79b0 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815cc846 RDI: ffffed101387af28
RBP: ffff88809c3d79d8 R08: ffff88805b02c600 R09: fffffbfff14efd54
R10: fffffbfff14efd53 R11: ffffffff8a77ea9f R12: ffff88809c3d7b20
R13: ffffffff87e12920 R14: 0000000000000002 R15: 000000000000001d
 apparmor_socket_sendmsg+0x2a/0x30 security/apparmor/lsm.c:936
 security_socket_sendmsg+0x77/0xc0 security/security.c:2013
 sock_sendmsg+0x45/0x130 net/socket.c:654
 kernel_sendmsg+0x44/0x50 net/socket.c:677
 rxrpc_send_keepalive+0x1ff/0x940 net/rxrpc/output.c:655
 rxrpc_peer_keepalive_dispatch net/rxrpc/peer_event.c:376 [inline]
 rxrpc_peer_keepalive_worker+0x7be/0xd02 net/rxrpc/peer_event.c:437
 process_one_work+0x9af/0x1740 kernel/workqueue.c:2269
 worker_thread+0x98/0xe40 kernel/workqueue.c:2415
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Kernel Offset: disabled
Rebooting in 86400 seconds..


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