[syzbot] [kernel?] WARNING: ODEBUG bug in vub300_disconnect

[syzbot <syzbot+f4a0159ce6802a0a4774@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    0a0d1d55dad5 Merge tag 'scftorture.2026.08.18a' of git://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=126be415580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=335632b21d0ce540
dashboard link: https://syzkaller.appspot.com/bug?extid=f4a0159ce6802a0a4774
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b00b3ccadcaf/disk-0a0d1d55.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0e672b557a64/vmlinux-0a0d1d55.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b5c1ac823fac/bzImage-0a0d1d55.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f4a0159ce6802a0a4774@syzkaller.appspotmail.com

------------[ cut here ]------------
ODEBUG: free active (active state 0) object: ffff888077279270 object type: timer_list hint: vub300_inactivity_timer_expired+0x0/0x3f0 include/linux/refcount.h:-1
WARNING: lib/debugobjects.c:632 at debug_print_object+0xec/0x230 lib/debugobjects.c:629, CPU#0: kworker/0:1/10
Modules linked in:
CPU: 0 UID: 0 PID: 10 Comm: kworker/0:1 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Workqueue: usb_hub_wq hub_event
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 6f 4f 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 53 75 92 0b 48 83 c4 10 5b 41 5c
RSP: 0018:ffffc900000f7218 EFLAGS: 00010246
RAX: 1ffffffff181ede4 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: ffffffff8c6d6340 RSI: ffffffff8c6d5dc0 RDI: ffffffff9084da30
RBP: ffffffff8c6d6340 R08: ffff888077279270 R09: ffffffff8c0f8280
R10: dffffc0000000000 R11: ffffffff81b32b80 R12: 0000000000000000
R13: ffffffff9084da30 R14: ffff888077279270 R15: ffffffff8c0f6f20
FS:  0000000000000000(0000) GS:ffff888124cf3000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5b6cbceff8 CR3: 000000000eb46000 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:2609 [inline]
 slab_free mm/slub.c:6372 [inline]
 kfree+0x13e/0x640 mm/slub.c:6687
 device_release+0xc4/0x1f0 drivers/base/core.c:-1
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x222/0x550 lib/kobject.c:737
 vub300_delete drivers/mmc/host/vub300.c:379 [inline]
 kref_put include/linux/kref.h:65 [inline]
 vub300_disconnect+0x280/0x2f0 drivers/mmc/host/vub300.c:2388
 usb_unbind_interface+0x295/0x9f0 drivers/usb/core/driver.c:458
 device_remove drivers/base/dd.c:618 [inline]
 __device_release_driver drivers/base/dd.c:1349 [inline]
 device_release_driver_internal+0x4f5/0x880 drivers/base/dd.c:1372
 bus_remove_device+0x444/0x560 drivers/base/bus.c:664
 device_del+0x524/0x8f0 drivers/base/core.c:3965
 usb_disable_device+0x3d4/0x8d0 drivers/usb/core/message.c:1478
 usb_disconnect+0x346/0x9a0 drivers/usb/core/hub.c:2345
 hub_port_connect drivers/usb/core/hub.c:5415 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5715 [inline]
 port_event drivers/usb/core/hub.c:5879 [inline]
 hub_event+0x1bbb/0x4d30 drivers/usb/core/hub.c:5961
 process_one_work kernel/workqueue.c:3387 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3470
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3551
 kthread+0x38b/0x480 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 6f 4f fd       	call   0xfd4f6f70
  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 53 75 92 0b    	incl   0xb927553(%rip)        # 0xb92758c
  39:	48 83 c4 10          	add    $0x10,%rsp
  3d:	5b                   	pop    %rbx
  3e:	41 5c                	pop    %r12


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup