[moderation] [cifs?] WARNING: ODEBUG bug in clean_demultiplex_info

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: dcb68831eac7 Merge tag 'block-7.2-20260815' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1345fa79580000
kernel config: https://syzkaller.appspot.com/x/.config?x=2ca5f2f2c4197664
dashboard link: https://syzkaller.appspot.com/bug?extid=4117399679308964d5ec
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
CC: [bhar...@microsoft.com linux...@vger.kernel.org linux-...@vger.kernel.org p...@manguebit.org ronnies...@gmail.com samba-t...@lists.samba.org sfr...@samba.org spr...@microsoft.com t...@talpey.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8b4c22458289/disk-dcb68831.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/650153fc7cdf/vmlinux-dcb68831.xz
kernel image: https://storage.googleapis.com/syzbot-assets/30612c9afef9/bzImage-dcb68831.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+411739...@syzkaller.appspotmail.com

------------[ cut here ]------------
ODEBUG: free active (active state 0) object: ffff88807f9825d8 object type: work_struct hint: smb2_reconnect_server+0x0/0x17b0 fs/smb/client/smb2pdu.c:-1
WARNING: lib/debugobjects.c:632 at debug_print_object+0xec/0x230 lib/debugobjects.c:629, CPU#0: cifsd/6027
Modules linked in:
CPU: 0 UID: 0 PID: 6027 Comm: cifsd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:debug_print_object+0x18a/0x230 lib/debugobjects.c:629
Code: f8 48 c1 e8 03 80 3c 18 00 74 08 4c 89 ff e8 5d 0a 56 fd 4d 8b 0f 4c 89 ef 48 8b 74 24 08 48 89 ea 44 89 e1 4d 89 f0 ff 34 24 <67> 48 0f b9 3a 48 83 c4 08 ff 05 a3 2e 79 0b 48 83 c4 10 5b 41 5c
RSP: 0018:ffffc90005607700 EFLAGS: 00010246
RAX: 1ffffffff17d6ce4 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: ffffffff8c4bca40 RSI: ffffffff8c4bc4c0 RDI: ffffffff9062f4e0
RBP: ffffffff8c4bca40 R08: ffff88807f9825d8 R09: ffffffff8beb78e0
R10: dffffc0000000000 R11: ffffffff818ef8a0 R12: 0000000000000000
R13: ffffffff9062f4e0 R14: ffff88807f9825d8 R15: ffffffff8beb6720
FS: 0000000000000000(0000) GS:ffff888124f49000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b3320cff8 CR3: 0000000059ce9000 CR4: 0000000000350ef0
Call Trace:
<TASK>
__debug_check_no_obj_freed lib/debugobjects.c:1171 [inline]
debug_check_no_obj_freed+0x2e3/0x450 lib/debugobjects.c:1201
slab_free_hook mm/slub.c:2608 [inline]
slab_free mm/slub.c:6377 [inline]
kfree+0x13e/0x640 mm/slub.c:6692
clean_demultiplex_info+0xb24/0xd30 fs/smb/client/connect.c:1146
cifs_demultiplex_thread+0x2fb9/0x3310 fs/smb/client/connect.c:1439
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
----------------
Code disassembly (best guess):
0: f8 clc
1: 48 c1 e8 03 shr $0x3,%rax
5: 80 3c 18 00 cmpb $0x0,(%rax,%rbx,1)
9: 74 08 je 0x13
b: 4c 89 ff mov %r15,%rdi
e: e8 5d 0a 56 fd call 0xfd560a70
13: 4d 8b 0f mov (%r15),%r9
16: 4c 89 ef mov %r13,%rdi
19: 48 8b 74 24 08 mov 0x8(%rsp),%rsi
1e: 48 89 ea mov %rbp,%rdx
21: 44 89 e1 mov %r12d,%ecx
24: 4d 89 f0 mov %r14,%r8
27: ff 34 24 push (%rsp)
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: 48 83 c4 08 add $0x8,%rsp
33: ff 05 a3 2e 79 0b incl 0xb792ea3(%rip) # 0xb792edc
39: 48 83 c4 10 add $0x10,%rsp
3d: 5b pop %rbx
3e: 41 5c pop %r12


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