general protection fault in selinux_socket_sendmsg (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    6b8a7946 Merge tag 'for_linus' of git://git.kernel.org/pub..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1680ab8ce00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4737c15fc47048f2
dashboard link: https://syzkaller.appspot.com/bug?extid=314db21f0d5c1f53856c
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+314db21f0d5c1f53856c@xxxxxxxxxxxxxxxxxxxxxxxxx

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 4616 Comm: kworker/1:0 Not tainted 5.4.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: krxrpcd rxrpc_peer_keepalive_worker
RIP: 0010:selinux_socket_sendmsg+0x22/0x40 security/selinux/hooks.c:4828
Code: c3 e8 c2 40 ac fe eb e8 55 48 89 e5 53 48 89 fb e8 43 d5 70 fe 48 8d  
7b 18 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75  
11 48 8b 7b 18 be 04 00 00 00 e8 fa fb ff ff 5b 5d
RSP: 0000:ffff888089fd79f0 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff83427eb5
RDX: 0000000000000003 RSI: ffffffff830281dd RDI: 0000000000000018
RBP: ffff888089fd79f8 R08: ffff888098698400 R09: fffffbfff14f0154
R10: fffffbfff14f0153 R11: ffffffff8a780a9f R12: dffffc0000000000
R13: ffff888089fd7b20 R14: ffff888089fd7b20 R15: 000000000000001d
FS:  0000000000000000(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c000064008 CR3: 00000000a87b8000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 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
Modules linked in:
---[ end trace f42fd501ecc72d8d ]---
RIP: 0010:selinux_socket_sendmsg+0x22/0x40 security/selinux/hooks.c:4828
Code: c3 e8 c2 40 ac fe eb e8 55 48 89 e5 53 48 89 fb e8 43 d5 70 fe 48 8d  
7b 18 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75  
11 48 8b 7b 18 be 04 00 00 00 e8 fa fb ff ff 5b 5d
RSP: 0000:ffff888089fd79f0 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff83427eb5
RDX: 0000000000000003 RSI: ffffffff830281dd RDI: 0000000000000018
RBP: ffff888089fd79f8 R08: ffff888098698400 R09: fffffbfff14f0154
R10: fffffbfff14f0153 R11: ffffffff8a780a9f R12: dffffc0000000000
R13: ffff888089fd7b20 R14: ffff888089fd7b20 R15: 000000000000001d
FS:  0000000000000000(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9c00057120 CR3: 00000000a3e31000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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