kernel BUG at lib/assoc_array.c:LINE!

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    46d6b7be Merge git://git.kernel.org/pub/scm/linux/kernel/g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11383a79e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6dda7ccc1e75a63f
dashboard link: https://syzkaller.appspot.com/bug?extid=23e14950fa7550d86091
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+23e14950fa7550d86091@xxxxxxxxxxxxxxxxxxxxxxxxx

------------[ cut here ]------------
kernel BUG at lib/assoc_array.c:652!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 2778 Comm: kworker/0:37 Not tainted 5.5.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: afs afs_manage_cell
RIP: 0010:assoc_array_insert_into_terminal_node lib/assoc_array.c:652 [inline]
RIP: 0010:assoc_array_insert+0x2baa/0x2bd0 lib/assoc_array.c:1001
Code: 0f 0b e8 a9 64 d4 fd 0f 0b e8 a2 64 d4 fd 0f 0b e8 9b 64 d4 fd 0f 0b e8 94 64 d4 fd 0f 0b e8 8d 64 d4 fd 0f 0b e8 86 64 d4 fd <0f> 0b e8 7f 64 d4 fd 0f 0b e8 78 64 d4 fd 0f 0b e8 71 64 d4 fd 0f
RSP: 0018:ffffc900087ff810 EFLAGS: 00010293
RAX: ffffffff83a25a7a RBX: 1ffff11012d568af RCX: ffff88809f34a580
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900087ff920 R08: ffffffff83a249fd R09: ffffffff83538f4f
R10: ffff88809f34a580 R11: 0000000000000004 R12: ffff888096ab4588
R13: ffff888096ab4500 R14: ffff888096ab4578 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000738000 CR3: 0000000054a3b000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __key_link_begin+0xfe/0x230 security/keys/keyring.c:1316
 construct_alloc_key security/keys/request_key.c:404 [inline]
 construct_key_and_link security/keys/request_key.c:499 [inline]
 request_key_and_link+0x9b6/0x1680 security/keys/request_key.c:637
 request_key_tag+0x53/0x190 security/keys/request_key.c:701
 dns_query+0x266/0x6c0 net/dns_resolver/dns_query.c:128
 afs_dns_query+0xdd/0x320 fs/afs/addr_list.c:249
 afs_update_cell fs/afs/cell.c:391 [inline]
 afs_manage_cell+0xda2/0x1500 fs/afs/cell.c:693
 process_one_work+0x7f5/0x10f0 kernel/workqueue.c:2264
 worker_thread+0xbbc/0x1630 kernel/workqueue.c:2410
 kthread+0x332/0x350 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Modules linked in:
---[ end trace 9dabb2deade74362 ]---
RIP: 0010:assoc_array_insert_into_terminal_node lib/assoc_array.c:652 [inline]
RIP: 0010:assoc_array_insert+0x2baa/0x2bd0 lib/assoc_array.c:1001
Code: 0f 0b e8 a9 64 d4 fd 0f 0b e8 a2 64 d4 fd 0f 0b e8 9b 64 d4 fd 0f 0b e8 94 64 d4 fd 0f 0b e8 8d 64 d4 fd 0f 0b e8 86 64 d4 fd <0f> 0b e8 7f 64 d4 fd 0f 0b e8 78 64 d4 fd 0f 0b e8 71 64 d4 fd 0f
RSP: 0018:ffffc900087ff810 EFLAGS: 00010293
RAX: ffffffff83a25a7a RBX: 1ffff11012d568af RCX: ffff88809f34a580
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900087ff920 R08: ffffffff83a249fd R09: ffffffff83538f4f
R10: ffff88809f34a580 R11: 0000000000000004 R12: ffff888096ab4588
R13: ffff888096ab4500 R14: ffff888096ab4578 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000013e4978 CR3: 000000008adb2000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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