[syzbot] kernel BUG in assoc_array_insert (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    7d549995d4e0 Merge tag 'for-linus' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17577e1a300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1dee114394f7d2c2
dashboard link: https://syzkaller.appspot.com/bug?extid=219c8d031f42380c907a
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+219c8d031f42380c907a at syzkaller.appspotmail.com

------------[ cut here ]------------
kernel BUG at lib/assoc_array.c:640!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 9793 Comm: kworker/1:8 Not tainted 5.14.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: afs afs_manage_cell_work
RIP: 0010:assoc_array_insert_into_terminal_node lib/assoc_array.c:640 [inline]
RIP: 0010:assoc_array_insert+0x1e3e/0x2e70 lib/assoc_array.c:1001
Code: 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 84 c4 fe ff ff e8 3c ac e0 fd e9 ba fe ff ff e8 02 f2 9a fd <0f> 0b e8 fb f1 9a fd 0f 0b e8 f4 f1 9a fd 0f 0b e8 ed f1 9a fd 0f
RSP: 0018:ffffc90009c177b0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 00000000000000ff RCX: 0000000000000000
RDX: ffff888087970100 RSI: ffffffff83d9cece RDI: 0000000000000003
RBP: 0000000000000011 R08: 0000000000000010 R09: 000000000000000f
R10: ffffffff83d9c0d9 R11: 000000000000000c R12: 00000000000000ff
R13: dffffc0000000000 R14: 0000000000000010 R15: 000000000000000c
FS:  0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1de4db0000 CR3: 0000000020468000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __key_link_begin+0xec/0x250 security/keys/keyring.c:1314
 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+0x798/0x1260 security/keys/request_key.c:637
 request_key_tag+0x4e/0xb0 security/keys/request_key.c:701
 dns_query+0x257/0x6d0 net/dns_resolver/dns_query.c:128
 afs_dns_query+0x122/0x390 fs/afs/addr_list.c:249
 afs_update_cell fs/afs/cell.c:402 [inline]
 afs_manage_cell fs/afs/cell.c:784 [inline]
 afs_manage_cell_work+0xa05/0x11f0 fs/afs/cell.c:840
 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
Modules linked in:
---[ end trace 02156db422e890c4 ]---
RIP: 0010:assoc_array_insert_into_terminal_node lib/assoc_array.c:640 [inline]
RIP: 0010:assoc_array_insert+0x1e3e/0x2e70 lib/assoc_array.c:1001
Code: 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 84 c4 fe ff ff e8 3c ac e0 fd e9 ba fe ff ff e8 02 f2 9a fd <0f> 0b e8 fb f1 9a fd 0f 0b e8 f4 f1 9a fd 0f 0b e8 ed f1 9a fd 0f
RSP: 0018:ffffc90009c177b0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 00000000000000ff RCX: 0000000000000000
RDX: ffff888087970100 RSI: ffffffff83d9cece RDI: 0000000000000003
RBP: 0000000000000011 R08: 0000000000000010 R09: 000000000000000f
R10: ffffffff83d9c0d9 R11: 000000000000000c R12: 00000000000000ff
R13: dffffc0000000000 R14: 0000000000000010 R15: 000000000000000c
FS:  0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000308a888 CR3: 000000007ed4e000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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