BUG: unable to handle kernel paging request in netlink_unicast

Hello,

syzbot found the following crash on:

HEAD commit:    b3a60822 Merge branch 'for-v5.6' of git://git.kernel.org:/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1477ae95e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5766bb49c0bc43b9
dashboard link: https://syzkaller.appspot.com/bug?extid=da7f30a2f1a15a687839
compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)

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+da7f30a2f1a15a687839@syzkaller.appspotmail.com

kernel tried to execute NX-protected page - exploit attempt? (uid: 0)
BUG: unable to handle page fault for address: ffff88809d910a50
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0011) - permissions violation
PGD b001067 P4D b001067 PUD 21ffff067 PMD 800000009d8001e3 
Oops: 0011 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 12558 Comm: syz-executor.2 Not tainted 5.5.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:0xffff88809d910a50
Code: 00 00 00 00 00 00 00 00 00 00 86 7a 03 89 ff ff ff ff 00 60 43 aa 80 88 ff ff 40 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 <50> f8 d1 04 00 c9 ff ff 70 55 a7 86 ff ff ff ff c0 81 e4 8c 80 88
RSP: 0018:ffffc90004d1f860 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffffff869eea30 RCX: dffffc0000000000
RDX: ffffc900024cb000 RSI: 0000000000005c7e RDI: 0000000000005c7f
RBP: ffffc90004d1fb20 R08: dffffc0000000000 R09: ffffed1014d22849
R10: ffffed1014d22849 R11: 0000000000000000 R12: 1ffff11013dabb07
R13: ffff88809ed5d83a R14: 000000000000006e R15: dffffc0000000000
FS:  00007f828b464700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff88809d910a50 CR3: 000000009c353000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
 netlink_unicast+0x766/0x920 net/netlink/af_netlink.c:1328
 netlink_sendmsg+0xa2b/0xd40 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 ____sys_sendmsg+0x4f7/0x7f0 net/socket.c:2343
 ___sys_sendmsg net/socket.c:2397 [inline]
 __sys_sendmsg+0x1ed/0x290 net/socket.c:2430
 __do_sys_sendmsg net/socket.c:2439 [inline]
 __se_sys_sendmsg net/socket.c:2437 [inline]
 __x64_sys_sendmsg+0x7f/0x90 net/socket.c:2437
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45b349
Code: ad b6 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 b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f828b463c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f828b4646d4 RCX: 000000000045b349
RDX: 0000000000000000 RSI: 0000000020003e00 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000940 R14: 00000000004ca9e5 R15: 000000000075bf2c
Modules linked in:
CR2: ffff88809d910a50
---[ end trace 71a7bd2ec42e29ac ]---
RIP: 0010:0xffff88809d910a50
Code: 00 00 00 00 00 00 00 00 00 00 86 7a 03 89 ff ff ff ff 00 60 43 aa 80 88 ff ff 40 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 <50> f8 d1 04 00 c9 ff ff 70 55 a7 86 ff ff ff ff c0 81 e4 8c 80 88
RSP: 0018:ffffc90004d1f860 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffffff869eea30 RCX: dffffc0000000000
RDX: ffffc900024cb000 RSI: 0000000000005c7e RDI: 0000000000005c7f
RBP: ffffc90004d1fb20 R08: dffffc0000000000 R09: ffffed1014d22849
R10: ffffed1014d22849 R11: 0000000000000000 R12: 1ffff11013dabb07
R13: ffff88809ed5d83a R14: 000000000000006e R15: dffffc0000000000
FS:  00007f828b464700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff88809d910a50 CR3: 000000009c353000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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