WARNING: kobject bug in pch_udc_remove

Status: moderation: reported on 2026/08/06 00:12
Subsystems: kernel
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+d0229c5127a8cfd2938b@syzkaller.appspotmail.com
First crash: 5d14h, last: 1d12h
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
3a87763d assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ✅ VMHostTrigger: ❌ ❓ WARNING: kobject bug in pch_udc_remove 2026/08/03 00:01 2026/08/03 00:01 2026/08/03 00:57 e611ffe1

Sample crash report:
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 1
CPU: 0 UID: 0 PID: 5331 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 fail_dump lib/fault-inject.c:73 [inline]
 should_fail_ex+0x40c/0x560 lib/fault-inject.c:174
 should_failslab+0xa8/0x100 mm/failslab.c:46
 slab_pre_alloc_hook mm/slub.c:4539 [inline]
 slab_alloc_node mm/slub.c:4897 [inline]
 __kmalloc_cache_noprof+0xa8/0x660 mm/slub.c:5485
 _kmalloc_noprof include/linux/slab.h:988 [inline]
 _kzalloc_noprof include/linux/slab.h:1309 [inline]
 acpi_ut_evaluate_object+0x97/0x560 drivers/acpi/acpica/uteval.c:50
 acpi_rs_get_prt_method_data+0xb2/0x150 drivers/acpi/acpica/rsutils.c:446
 acpi_get_irq_routing_table+0x98/0xe0 drivers/acpi/acpica/rsxface.c:137
 acpi_pci_irq_find_prt_entry+0x163/0x1040 drivers/acpi/pci_irq.c:215
 acpi_pci_irq_lookup+0x45/0x690 drivers/acpi/pci_irq.c:299
 acpi_pci_irq_enable+0x1ee/0x7a0 drivers/acpi/pci_irq.c:414
 do_pci_enable_device+0x26f/0x4a0 drivers/pci/pci.c:1998
 pci_enable_device_flags+0x5ab/0x700 drivers/pci/pci.c:2089
 pcim_enable_device+0x4e/0xe0 drivers/pci/devres.c:383
 pch_udc_probe+0x73/0x1690 drivers/usb/gadget/udc/pch_udc.c:3050
 local_pci_probe drivers/pci/pci-driver.c:332 [inline]
 pci_call_probe drivers/pci/pci-driver.c:394 [inline]
 __pci_device_probe drivers/pci/pci-driver.c:455 [inline]
 pci_device_probe+0x431/0xc90 drivers/pci/pci-driver.c:489
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x254/0xae0 drivers/base/dd.c:706
 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:868
 device_driver_attach+0xe0/0x1d0 drivers/base/dd.c:1203
 bind_store+0x1d0/0x220 drivers/base/bus.c:267
 kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb737b9e019
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb738a31fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fb737e26090 RCX: 00007fb737b9e019
RDX: 000000000000000c RSI: 0000200000000240 RDI: 0000000000000005
RBP: 00007fb738a32050 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fb737e26128 R14: 00007fb737e26090 R15: 00007fff0b00dca8
 </TASK>
pch_udc 0000:00:03.0: can't derive routing for PCI INT A
pch_udc 0000:00:03.0: PCI INT A: no GSI
pch_udc 0000:00:03.0: error -EINVAL: request_irq(23) pch_udc_isr 0x0 pch_udc
pch_udc 0000:00:03.0: pch_udc_probe: request_irq(23) fail
------------[ cut here ]------------
kobject: '(null)' (ffff888012820110): is not initialized, yet kobject_put() is being called.
WARNING: lib/kobject.c:736 at kobject_put+0x66/0x550 lib/kobject.c:734, CPU#0: syz.0.0/5331
Modules linked in:
CPU: 0 UID: 0 PID: 5331 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:kobject_put+0x8e/0x550 lib/kobject.c:734
Code: a0 04 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 48 89 df e8 0b 09 6c f6 48 8b 33 4c 89 f7 48 89 da <67> 48 0f b9 3a eb 05 e8 56 d6 fc f5 4c 8d 73 38 4c 89 f7 be 04 00
RSP: 0018:ffffc9000e37f830 EFLAGS: 00010246
RAX: 1ffff11002504022 RBX: ffff888012820110 RCX: dffffc0000000000
RDX: ffff888012820110 RSI: 0000000000000000 RDI: ffffffff906afa70
RBP: 0000000000000000 R08: ffffc9000e37f407 R09: 1ffff92001c6fe80
R10: dffffc0000000000 R11: fffff52001c6fe81 R12: 1ffff11002504029
R13: dffffc0000000000 R14: ffffffff906afa70 R15: ffff88801f87c000
FS:  00007fb738a326c0(0000) GS:ffff88808c53f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb738a5c230 CR3: 00000000426e6000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 pch_udc_remove+0x48/0x3c0 drivers/usb/gadget/udc/pch_udc.c:2986
 pch_udc_probe+0x14c5/0x1690 drivers/usb/gadget/udc/pch_udc.c:3109
 local_pci_probe drivers/pci/pci-driver.c:332 [inline]
 pci_call_probe drivers/pci/pci-driver.c:394 [inline]
 __pci_device_probe drivers/pci/pci-driver.c:455 [inline]
 pci_device_probe+0x431/0xc90 drivers/pci/pci-driver.c:489
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x254/0xae0 drivers/base/dd.c:706
 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:868
 device_driver_attach+0xe0/0x1d0 drivers/base/dd.c:1203
 bind_store+0x1d0/0x220 drivers/base/bus.c:267
 kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb737b9e019
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb738a31fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fb737e26090 RCX: 00007fb737b9e019
RDX: 000000000000000c RSI: 0000200000000240 RDI: 0000000000000005
RBP: 00007fb738a32050 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fb737e26128 R14: 00007fb737e26090 R15: 00007fff0b00dca8
 </TASK>
----------------
Code disassembly (best guess):
   0:	a0 04 48 89 d8 48 c1 	movabs 0x3e8c148d8894804,%al
   7:	e8 03
   9:	48 b9 00 00 00 00 00 	movabs $0xdffffc0000000000,%rcx
  10:	fc ff df
  13:	80 3c 08 00          	cmpb   $0x0,(%rax,%rcx,1)
  17:	74 08                	je     0x21
  19:	48 89 df             	mov    %rbx,%rdi
  1c:	e8 0b 09 6c f6       	call   0xf66c092c
  21:	48 8b 33             	mov    (%rbx),%rsi
  24:	4c 89 f7             	mov    %r14,%rdi
  27:	48 89 da             	mov    %rbx,%rdx
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	eb 05                	jmp    0x36
  31:	e8 56 d6 fc f5       	call   0xf5fcd68c
  36:	4c 8d 73 38          	lea    0x38(%rbx),%r14
  3a:	4c 89 f7             	mov    %r14,%rdi
  3d:	be                   	.byte 0xbe
  3e:	04 00                	add    $0x0,%al

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/02 05:07 upstream 2d2338c93da7 e611ffe1 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING: kobject bug in pch_udc_remove
2026/08/05 19:11 upstream c21bb4193868 1eed00d1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING: kobject bug in pch_udc_remove
2026/08/01 17:01 upstream 02dc699f83d0 e611ffe1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING: kobject bug in pch_udc_remove
* Struck through repros no longer work on HEAD.