syzbot


KASAN: use-after-free Read in dummy_timer

Status: upstream: reported on 2025/05/26 00:26
Reported-by: syzbot+a6647823574145ef4dea@syzkaller.appspotmail.com
First crash: 5d11h, last: 5d11h
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream general protection fault in dummy_timer (2) usb syz 21 10d 188d 0/28 upstream: reported syz repro on 2024/11/24 05:03
upstream general protection fault in dummy_timer usb 2 561d 607d 0/28 auto-obsoleted due to no activity on 2024/02/14 16:35

Sample crash report:
smsusb:smsusb_onresponse: error, urb status -71, 0 bytes
smsusb:smsusb_onresponse: error, urb status -71, 0 bytes
smsusb:smsusb_onresponse: error, urb status -71, 0 bytes
smsusb:smsusb_onresponse: error, urb status -71, 0 bytes
==================================================================
BUG: KASAN: use-after-free in dummy_timer+0x263e/0x2e10 drivers/usb/gadget/udc/dummy_hcd.c:1843
Read of size 4 at addr ffff888016a98154 by task kworker/1:1/24

CPU: 1 PID: 24 Comm: kworker/1:1 Not tainted 5.15.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: usb_hub_wq hub_event
Call Trace:
 <IRQ>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 dummy_timer+0x263e/0x2e10 drivers/usb/gadget/udc/dummy_hcd.c:1843
 call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
 expire_timers kernel/time/timer.c:1496 [inline]
 __run_timers+0x525/0x7c0 kernel/time/timer.c:1767
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
 handle_softirqs+0x328/0x820 kernel/softirq.c:558
 __do_softirq kernel/softirq.c:592 [inline]
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:641
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:653
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:preempt_schedule_irq+0xac/0x150 kernel/sched/core.c:6780
Code: 44 24 20 f6 44 24 21 02 74 0b 0f 0b 48 f7 03 08 00 00 00 74 70 bf 01 00 00 00 e8 bf f4 a7 f7 e8 4a 76 d4 f7 fb bf 01 00 00 00 <e8> cf b5 ff ff 48 c7 44 24 40 00 00 00 00 9c 8f 44 24 40 8b 44 24
RSP: 0018:ffffc90000dee880 EFLAGS: 00000282
RAX: d9e5f3137510b800 RBX: 0000000000000000 RCX: d9e5f3137510b800
RDX: dffffc0000000000 RSI: ffffffff8a0b11c0 RDI: 0000000000000001
RBP: ffffc90000dee920 R08: dffffc0000000000 R09: fffffbfff1ff3644
R10: fffffbfff1ff3644 R11: 1ffffffff1ff3643 R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffff920001bdd10
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:681
RIP: 0010:lock_acquire+0x1f2/0x3f0 kernel/locking/lockdep.c:5627
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f6 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b
RSP: 0018:ffffc90000dee9e0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: d9e5f3137510b800
RDX: ffffffff8f9a6230 RSI: ffffffff8a0b2460 RDI: ffffffff8a59a700
RBP: ffffc90000deeae8 R08: dffffc0000000000 R09: fffffbfff250747c
R10: fffffbfff250747c R11: 1ffffffff250747b R12: ffff888022f63ae8
R13: 1ffff920001bdd48 R14: 0000000000000246 R15: dffffc0000000000
 kernfs_drain fs/kernfs/dir.c:478 [inline]
 __kernfs_remove+0x5de/0xc50 fs/kernfs/dir.c:1372
 kernfs_remove_by_name_ns+0x91/0x100 fs/kernfs/dir.c:1566
 media_device_unregister+0x361/0x3f0 drivers/media/mc/mc-device.c:846
 smsusb_init_device drivers/media/usb/siano/smsusb.c:493 [inline]
 smsusb_probe+0x16b2/0x1d10 drivers/media/usb/siano/smsusb.c:569
 usb_probe_interface+0x5a0/0xaf0 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x284/0xc80 drivers/base/dd.c:595
 __driver_probe_device+0x18c/0x330 drivers/base/dd.c:755
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:785
 __device_attach_driver+0x2b0/0x500 drivers/base/dd.c:907
 bus_for_each_drv+0x175/0x200 drivers/base/bus.c:429
 __device_attach+0x29b/0x460 drivers/base/dd.c:979
 bus_probe_device+0xbc/0x1e0 drivers/base/bus.c:489
 device_add+0xa00/0xfb0 drivers/base/core.c:3412
 usb_set_configuration+0x1991/0x1fd0 drivers/usb/core/message.c:2165
 usb_generic_driver_probe+0x89/0x150 drivers/usb/core/generic.c:238
 usb_probe_device+0x139/0x270 drivers/usb/core/driver.c:293
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x284/0xc80 drivers/base/dd.c:595
 __driver_probe_device+0x18c/0x330 drivers/base/dd.c:755
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:785
 __device_attach_driver+0x2b0/0x500 drivers/base/dd.c:907
 bus_for_each_drv+0x175/0x200 drivers/base/bus.c:429
 __device_attach+0x29b/0x460 drivers/base/dd.c:979
 bus_probe_device+0xbc/0x1e0 drivers/base/bus.c:489
 device_add+0xa00/0xfb0 drivers/base/core.c:3412
 usb_new_device+0xd53/0x1640 drivers/usb/core/hub.c:2604
 hub_port_connect drivers/usb/core/hub.c:5467 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 port_event drivers/usb/core/hub.c:5753 [inline]
 hub_event+0x295c/0x4fa0 drivers/usb/core/hub.c:5835
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Allocated by task 24:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 __kasan_kmalloc+0xb5/0xf0 mm/kasan/common.c:522
 kmalloc include/linux/slab.h:604 [inline]
 kzalloc include/linux/slab.h:735 [inline]
 smsusb_init_device drivers/media/usb/siano/smsusb.c:397 [inline]
 smsusb_probe+0x818/0x1d10 drivers/media/usb/siano/smsusb.c:569
 usb_probe_interface+0x5a0/0xaf0 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x284/0xc80 drivers/base/dd.c:595
 __driver_probe_device+0x18c/0x330 drivers/base/dd.c:755
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:785
 __device_attach_driver+0x2b0/0x500 drivers/base/dd.c:907
 bus_for_each_drv+0x175/0x200 drivers/base/bus.c:429
 __device_attach+0x29b/0x460 drivers/base/dd.c:979
 bus_probe_device+0xbc/0x1e0 drivers/base/bus.c:489
 device_add+0xa00/0xfb0 drivers/base/core.c:3412
 usb_set_configuration+0x1991/0x1fd0 drivers/usb/core/message.c:2165
 usb_generic_driver_probe+0x89/0x150 drivers/usb/core/generic.c:238
 usb_probe_device+0x139/0x270 drivers/usb/core/driver.c:293
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x284/0xc80 drivers/base/dd.c:595
 __driver_probe_device+0x18c/0x330 drivers/base/dd.c:755
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:785
 __device_attach_driver+0x2b0/0x500 drivers/base/dd.c:907
 bus_for_each_drv+0x175/0x200 drivers/base/bus.c:429
 __device_attach+0x29b/0x460 drivers/base/dd.c:979
 bus_probe_device+0xbc/0x1e0 drivers/base/bus.c:489
 device_add+0xa00/0xfb0 drivers/base/core.c:3412
 usb_new_device+0xd53/0x1640 drivers/usb/core/hub.c:2604
 hub_port_connect drivers/usb/core/hub.c:5467 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 port_event drivers/usb/core/hub.c:5753 [inline]
 hub_event+0x295c/0x4fa0 drivers/usb/core/hub.c:5835
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

Freed by task 24:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1705 [inline]
 slab_free_freelist_hook+0xea/0x170 mm/slub.c:1731
 slab_free mm/slub.c:3499 [inline]
 kfree+0xef/0x2a0 mm/slub.c:4559
 smsusb_term_device+0x1ac/0x220 drivers/media/usb/siano/smsusb.c:352
 smsusb_init_device drivers/media/usb/siano/smsusb.c:491 [inline]
 smsusb_probe+0x16aa/0x1d10 drivers/media/usb/siano/smsusb.c:569
 usb_probe_interface+0x5a0/0xaf0 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x284/0xc80 drivers/base/dd.c:595
 __driver_probe_device+0x18c/0x330 drivers/base/dd.c:755
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:785
 __device_attach_driver+0x2b0/0x500 drivers/base/dd.c:907
 bus_for_each_drv+0x175/0x200 drivers/base/bus.c:429
 __device_attach+0x29b/0x460 drivers/base/dd.c:979
 bus_probe_device+0xbc/0x1e0 drivers/base/bus.c:489
 device_add+0xa00/0xfb0 drivers/base/core.c:3412
 usb_set_configuration+0x1991/0x1fd0 drivers/usb/core/message.c:2165
 usb_generic_driver_probe+0x89/0x150 drivers/usb/core/generic.c:238
 usb_probe_device+0x139/0x270 drivers/usb/core/driver.c:293
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x284/0xc80 drivers/base/dd.c:595
 __driver_probe_device+0x18c/0x330 drivers/base/dd.c:755
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:785
 __device_attach_driver+0x2b0/0x500 drivers/base/dd.c:907
 bus_for_each_drv+0x175/0x200 drivers/base/bus.c:429
 __device_attach+0x29b/0x460 drivers/base/dd.c:979
 bus_probe_device+0xbc/0x1e0 drivers/base/bus.c:489
 device_add+0xa00/0xfb0 drivers/base/core.c:3412
 usb_new_device+0xd53/0x1640 drivers/usb/core/hub.c:2604
 hub_port_connect drivers/usb/core/hub.c:5467 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5607 [inline]
 port_event drivers/usb/core/hub.c:5753 [inline]
 hub_event+0x295c/0x4fa0 drivers/usb/core/hub.c:5835
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

Last potentially related work creation:
 kasan_save_stack+0x35/0x60 mm/kasan/common.c:38
 kasan_record_aux_stack+0xb8/0x100 mm/kasan/generic.c:348
 insert_work+0x54/0x3d0 kernel/workqueue.c:1366
 __queue_work+0x9c5/0xd50 kernel/workqueue.c:1532
 queue_work_on+0x11d/0x1d0 kernel/workqueue.c:1559
 __usb_hcd_giveback_urb+0x35f/0x520 drivers/usb/core/hcd.c:1674
 dummy_timer+0x827/0x2e10 drivers/usb/gadget/udc/dummy_hcd.c:1987
 call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
 expire_timers kernel/time/timer.c:1496 [inline]
 __run_timers+0x525/0x7c0 kernel/time/timer.c:1767
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
 handle_softirqs+0x328/0x820 kernel/softirq.c:558
 __do_softirq kernel/softirq.c:592 [inline]
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:641
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:653
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x52/0xc0 arch/x86/kernel/apic/apic.c:1108
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676

Second to last potentially related work creation:
 kasan_save_stack+0x35/0x60 mm/kasan/common.c:38
 kasan_record_aux_stack+0xb8/0x100 mm/kasan/generic.c:348
 insert_work+0x54/0x3d0 kernel/workqueue.c:1366
 __queue_work+0x9c5/0xd50 kernel/workqueue.c:1532
 queue_work_on+0x11d/0x1d0 kernel/workqueue.c:1559
 __usb_hcd_giveback_urb+0x35f/0x520 drivers/usb/core/hcd.c:1674
 dummy_timer+0x827/0x2e10 drivers/usb/gadget/udc/dummy_hcd.c:1987
 call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
 expire_timers kernel/time/timer.c:1496 [inline]
 __run_timers+0x525/0x7c0 kernel/time/timer.c:1767
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
 handle_softirqs+0x328/0x820 kernel/softirq.c:558
 __do_softirq kernel/softirq.c:592 [inline]
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:641
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:653
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x52/0xc0 arch/x86/kernel/apic/apic.c:1108
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676

The buggy address belongs to the object at ffff888016a98000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 340 bytes inside of
 4096-byte region [ffff888016a98000, ffff888016a99000)
The buggy address belongs to the page:
page:ffffea00005aa600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16a98
head:ffffea00005aa600 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 0000000100000001 ffff888016842140
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, ts 1882153078, free_ts 0
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x1b77/0x1c60 mm/page_alloc.c:4192
 __alloc_pages+0x1e1/0x470 mm/page_alloc.c:5466
 alloc_page_interleave+0x24/0x1e0 mm/mempolicy.c:2031
 alloc_slab_page mm/slub.c:1775 [inline]
 allocate_slab mm/slub.c:1912 [inline]
 new_slab+0xc0/0x4b0 mm/slub.c:1975
 ___slab_alloc+0x81e/0xdf0 mm/slub.c:3008
 __slab_alloc mm/slub.c:3095 [inline]
 slab_alloc_node mm/slub.c:3186 [inline]
 slab_alloc mm/slub.c:3228 [inline]
 kmem_cache_alloc_trace+0x1a5/0x2a0 mm/slub.c:3245
 kmalloc include/linux/slab.h:604 [inline]
 kzalloc include/linux/slab.h:735 [inline]
 kobject_uevent_env+0x27a/0x890 lib/kobject_uevent.c:539
 kset_register+0x170/0x1d0 lib/kobject.c:894
 bus_register+0x21c/0x6c0 drivers/base/bus.c:808
 subsys_register+0x20/0x1c0 drivers/base/bus.c:1089
 wq_sysfs_init+0x14/0x50 kernel/workqueue.c:5743
 do_one_initcall+0x1ee/0x680 init/main.c:1302
 do_initcall_level+0x137/0x1f0 init/main.c:1375
 do_initcalls+0x4b/0x90 init/main.c:1391
 kernel_init_freeable+0x3ce/0x560 init/main.c:1615
 kernel_init+0x19/0x1b0 init/main.c:1506
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888016a98000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888016a98080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888016a98100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                 ^
 ffff888016a98180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888016a98200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
   0:	44 24 20             	rex.R and $0x20,%al
   3:	f6 44 24 21 02       	testb  $0x2,0x21(%rsp)
   8:	74 0b                	je     0x15
   a:	0f 0b                	ud2
   c:	48 f7 03 08 00 00 00 	testq  $0x8,(%rbx)
  13:	74 70                	je     0x85
  15:	bf 01 00 00 00       	mov    $0x1,%edi
  1a:	e8 bf f4 a7 f7       	call   0xf7a7f4de
  1f:	e8 4a 76 d4 f7       	call   0xf7d4766e
  24:	fb                   	sti
  25:	bf 01 00 00 00       	mov    $0x1,%edi
* 2a:	e8 cf b5 ff ff       	call   0xffffb5fe <-- trapping instruction
  2f:	48 c7 44 24 40 00 00 	movq   $0x0,0x40(%rsp)
  36:	00 00
  38:	9c                   	pushf
  39:	8f 44 24 40          	pop    0x40(%rsp)
  3d:	8b                   	.byte 0x8b
  3e:	44                   	rex.R
  3f:	24                   	.byte 0x24

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/26 00:26 linux-5.15.y 98f47d0e9b8c 2d4582d0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: use-after-free Read in dummy_timer
* Struck through repros no longer work on HEAD.