WARNING in __xlate_proc_name (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    b07f636f Merge tag 'tpmdd-next-20200108' of git://git.infr..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1293f549e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=18698c0c240ba616
dashboard link: https://syzkaller.appspot.com/bug?extid=016c7186c1d55575bab8
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13babc85e00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14b14d15e00000

The bug was bisected to:

commit 989782dcdc91a5e6d5999c7a52a84a60a0811e56
Author: David Howells <dhowells@xxxxxxxxxx>
Date:   Thu Nov 2 15:27:50 2017 +0000

    afs: Overhaul cell database management

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=12052156e00000
final crash:    https://syzkaller.appspot.com/x/report.txt?x=11052156e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=16052156e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+016c7186c1d55575bab8@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 989782dcdc91 ("afs: Overhaul cell database management")

------------[ cut here ]------------
name 'ïå0=ïïï#ïz
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WARNING: CPU: 1 PID: 2669 at fs/proc/generic.c:178 __xlate_proc_name  
fs/proc/generic.c:178 [inline]
WARNING: CPU: 1 PID: 2669 at fs/proc/generic.c:178  
__xlate_proc_name+0xe7/0x110 fs/proc/generic.c:161
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 2669 Comm: kworker/1:2 Not tainted 5.5.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: afs afs_manage_cell
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/0x3e kernel/panic.c:582
 report_bug+0x289/0x300 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:174 [inline]
 fixup_bug arch/x86/kernel/traps.c:169 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267
 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:__xlate_proc_name fs/proc/generic.c:178 [inline]
RIP: 0010:__xlate_proc_name+0xe7/0x110 fs/proc/generic.c:161
Code: 3f eb 90 ff 44 89 e0 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8  
28 eb 90 ff 4c 89 fe 48 c7 c7 40 18 39 88 e8 88 99 61 ff <0f> 0b 41 bc fe  
ff ff ff eb cb 4c 89 f7 e8 37 a4 ce ff e9 3d ff ff
RSP: 0018:ffffc900079bf9d0 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff888094ea3d49 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815e8506 RDI: fffff52000f37f2c
RBP: ffffc900079bfa00 R08: ffff8880a0aa6480 R09: fffffbfff165eba6
R10: fffffbfff165eba5 R11: ffffffff8b2f5d2f R12: 0000000000000000
R13: ffff888094ea3d39 R14: ffffc900079bfb08 R15: ffff888094ea3d39
 xlate_proc_name fs/proc/generic.c:194 [inline]
 __proc_create+0xac/0x860 fs/proc/generic.c:387
 proc_mkdir_data+0xbc/0x1b0 fs/proc/generic.c:473
 proc_net_mkdir include/linux/proc_fs.h:139 [inline]
 afs_proc_cell_setup+0x95/0x190 fs/afs/proc.c:610
 afs_activate_cell fs/afs/cell.c:591 [inline]
 afs_manage_cell+0x54b/0x1410 fs/afs/cell.c:673
 process_one_work+0x9af/0x1740 kernel/workqueue.c:2264
 worker_thread+0x98/0xe40 kernel/workqueue.c:2410
 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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