WARNING: ODEBUG bug in clean_demultiplex_info

Status: upstream: reported on 2026/08/18 11:49
Reported-by: syzbot+073e4edfc2c9fd464c2b@syzkaller.appspotmail.com
First crash: 8d01h, last: 8d01h
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING: ODEBUG bug in clean_demultiplex_info cifs prio:high -1 1 9d06h 5d06h 0/29 moderation: reported on 2026/08/21 06:57

Sample crash report:
------------[ cut here ]------------
ODEBUG: free active (active state 0) object: ffff88804f7ac5b8 object type: work_struct hint: smb2_reconnect_server+0x0/0x13d0
WARNING: CPU: 1 PID: 17400 at lib/debugobjects.c:518 debug_print_object lib/debugobjects.c:515 [inline]
WARNING: CPU: 1 PID: 17400 at lib/debugobjects.c:518 __debug_check_no_obj_freed lib/debugobjects.c:1045 [inline]
WARNING: CPU: 1 PID: 17400 at lib/debugobjects.c:518 debug_check_no_obj_freed+0x39f/0x520 lib/debugobjects.c:1075
Modules linked in:
CPU: 1 PID: 17400 Comm: cifsd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:debug_print_object lib/debugobjects.c:515 [inline]
RIP: 0010:__debug_check_no_obj_freed lib/debugobjects.c:1045 [inline]
RIP: 0010:debug_check_no_obj_freed+0x39f/0x520 lib/debugobjects.c:1075
Code: 8b 4d 00 48 c7 c7 a0 3c 1d 8b 48 c7 c6 00 39 1d 8b 48 c7 c2 20 3e 1d 8b 8b 4c 24 1c 4d 89 f8 41 55 e8 c5 70 16 fd 48 83 c4 08 <0f> 0b 4c 8b 6c 24 10 48 b9 00 00 00 00 00 fc ff df ff 05 8a dd 51
RSP: 0018:ffffc9000cb57818 EFLAGS: 00010286
RAX: d302b8f991ab6a00 RBX: ffffffff975bb748 RCX: ffff888028ea5a00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffffff8ac9f8c0 R08: ffffc9000cb57407 R09: 1ffff9200196ae80
R10: dffffc0000000000 R11: fffff5200196ae81 R12: 0000000000000001
R13: ffffffff82a7e090 R14: ffff88804f7ac000 R15: ffff88804f7ac5b8
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c3d4b0e CR3: 00000000523b7000 CR4: 00000000003526e0
Call Trace:
 <TASK>
 slab_free_hook mm/slub.c:1786 [inline]
 slab_free_freelist_hook+0xd2/0x1a0 mm/slub.c:1837
 slab_free mm/slub.c:3830 [inline]
 __kmem_cache_free+0xba/0x1f0 mm/slub.c:3843
 clean_demultiplex_info+0xb63/0xd60 fs/smb/client/connect.c:1078
 cifs_demultiplex_thread+0x274e/0x2a70 fs/smb/client/connect.c:1373
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/18 11:48 linux-6.6.y d27334b2888c 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING: ODEBUG bug in clean_demultiplex_info
* Struck through repros no longer work on HEAD.