[v5.15] KASAN: use-after-free Write in __run_timers

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12:05 AM (7 hours ago) 12:05 AM
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Hello,

syzbot found the following issue on:

HEAD commit: 68efe5a6c16a Linux 5.15.197
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15b5561a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7e6ed99963d6ee1d
dashboard link: https://syzkaller.appspot.com/bug?extid=67aa817ae7362047af2c
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16b85592580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11b85592580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/900f9b9bd850/disk-68efe5a6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1e089a5019a6/vmlinux-68efe5a6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b319f477b907/bzImage-68efe5a6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+67aa81...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in hlist_move_list include/linux/list.h:986 [inline]
BUG: KASAN: use-after-free in collect_expired_timers kernel/time/timer.c:1517 [inline]
BUG: KASAN: use-after-free in __run_timers+0x311/0x7c0 kernel/time/timer.c:1753
Write of size 8 at addr ffff88814635a848 by task kworker/1:6/4344

CPU: 1 PID: 4344 Comm: kworker/1:6 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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
hlist_move_list include/linux/list.h:986 [inline]
collect_expired_timers kernel/time/timer.c:1517 [inline]
__run_timers+0x311/0x7c0 kernel/time/timer.c:1753
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
handle_softirqs+0x328/0x820 kernel/softirq.c:576
__do_softirq kernel/softirq.c:610 [inline]
invoke_softirq kernel/softirq.c:450 [inline]
__irq_exit_rcu+0x12f/0x220 kernel/softirq.c:659
irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
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: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:ffffc900032de660 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: bef0aa2cf241da00
RDX: 0000000000000000 RSI: ffffffff8a0b2e80 RDI: ffffffff8a59e800
RBP: ffffc900032de778 R08: dffffc0000000000 R09: fffffbfff1ff541b
R10: fffffbfff1ff541b R11: 1ffffffff1ff541a R12: ffffffff8c1ece20
R13: 1ffff9200065bcd8 R14: 0000000000000246 R15: dffffc0000000000
fs_reclaim_acquire+0x91/0x100 mm/page_alloc.c:4597
might_alloc include/linux/sched/mm.h:206 [inline]
slab_pre_alloc_hook+0x20/0xc0 mm/slab.h:492
slab_alloc_node mm/slub.c:3139 [inline]
slab_alloc mm/slub.c:3233 [inline]
__kmalloc_track_caller+0x69/0x330 mm/slub.c:4930
kstrdup mm/util.c:60 [inline]
kstrdup_const+0x51/0x90 mm/util.c:83
__kernfs_new_node+0x9b/0x680 fs/kernfs/dir.c:589
kernfs_new_node+0x148/0x250 fs/kernfs/dir.c:669
kernfs_create_link+0xa3/0x200 fs/kernfs/symlink.c:39
sysfs_do_create_link_sd+0x83/0x110 fs/sysfs/symlink.c:44
device_add_class_symlinks drivers/base/core.c:3154 [inline]
device_add+0x7ed/0xfb0 drivers/base/core.c:3360
snd_register_device+0x32c/0x480 sound/core/sound.c:281
snd_rawmidi_dev_register+0x308/0xe60 sound/core/rawmidi.c:1884
__snd_device_register sound/core/device.c:149 [inline]
snd_device_register_all+0xc8/0x190 sound/core/device.c:197
snd_card_register+0x1a9/0x6c0 sound/core/init.c:903
try_to_register_card+0x299/0x320 sound/usb/card.c:-1
usb_audio_probe+0x17f8/0x1d50 sound/usb/card.c:930
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:2632
hub_port_connect drivers/usb/core/hub.c:5497 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5637 [inline]
port_event drivers/usb/core/hub.c:5799 [inline]
hub_event+0x2dd9/0x5560 drivers/usb/core/hub.c:5881
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 4190:
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:607 [inline]
kzalloc include/linux/slab.h:738 [inline]
__snd_usbmidi_create+0xda/0x2f90 sound/usb/midi.c:2539
snd_usb_create_quirk sound/usb/quirks.c:577 [inline]
create_composite_quirk+0x1ec/0x4e0 sound/usb/quirks.c:48
usb_audio_probe+0xb72/0x1d50 sound/usb/card.c:885
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:2632
hub_port_connect drivers/usb/core/hub.c:5497 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5637 [inline]
port_event drivers/usb/core/hub.c:5799 [inline]
hub_event+0x2dd9/0x5560 drivers/usb/core/hub.c:5881
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 4190:
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:1710 [inline]
slab_free_freelist_hook+0xea/0x170 mm/slub.c:1736
slab_free mm/slub.c:3504 [inline]
kfree+0xef/0x2a0 mm/slub.c:4564
snd_rawmidi_free+0x3b7/0x3e0 sound/core/rawmidi.c:1844
snd_rawmidi_dev_free+0x34/0x40 sound/core/rawmidi.c:1853
__snd_device_free+0x1cd/0x2e0 sound/core/device.c:76
snd_device_free_all+0xcb/0x180 sound/core/device.c:233
snd_card_do_free sound/core/init.c:588 [inline]
release_card_device+0x6d/0x1f0 sound/core/init.c:145
device_release+0x92/0x1c0 drivers/base/core.c:-1
kobject_cleanup lib/kobject.c:713 [inline]
kobject_release lib/kobject.c:744 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x21d/0x460 lib/kobject.c:761
snd_card_free_when_closed sound/core/init.c:620 [inline]
snd_card_free+0x123/0x190 sound/core/init.c:653
usb_audio_probe+0x187f/0x1d50 sound/usb/card.c:939
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:2632
hub_port_connect drivers/usb/core/hub.c:5497 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5637 [inline]
port_event drivers/usb/core/hub.c:5799 [inline]
hub_event+0x2dd9/0x5560 drivers/usb/core/hub.c:5881
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
__call_rcu kernel/rcu/tree.c:3011 [inline]
call_rcu+0x182/0x930 kernel/rcu/tree.c:3091
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

The buggy address belongs to the object at ffff88814635a800
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 72 bytes inside of
1024-byte region [ffff88814635a800, ffff88814635ac00)
The buggy address belongs to the page:
page:ffffea000518d600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x146358
head:ffffea000518d600 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x57ff00000010200(slab|head|node=1|zone=2|lastcpupid=0x7ff)
raw: 057ff00000010200 ffffea0001871e00 0000000300000003 ffff888016841dc0
raw: 0000000000000000 0000000000100010 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 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 4205, ts 78095644272, free_ts 77861086038
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:5487
__alloc_pages_node include/linux/gfp.h:570 [inline]
alloc_slab_page mm/slub.c:1782 [inline]
allocate_slab mm/slub.c:1917 [inline]
new_slab+0xb6/0x4b0 mm/slub.c:1980
___slab_alloc+0x81e/0xdf0 mm/slub.c:3013
__slab_alloc mm/slub.c:3100 [inline]
slab_alloc_node mm/slub.c:3191 [inline]
__kmalloc_node+0x200/0x3b0 mm/slub.c:4456
kmalloc_node include/linux/slab.h:630 [inline]
kvmalloc_node+0x84/0x130 mm/util.c:619
kvzalloc_node include/linux/mm.h:820 [inline]
alloc_shrinker_info+0xef/0x3b0 mm/vmscan.c:278
mem_cgroup_css_online+0x18/0x1d0 mm/memcontrol.c:5333
online_css+0xb9/0x260 kernel/cgroup/cgroup.c:5338
css_create kernel/cgroup/cgroup.c:5409 [inline]
cgroup_apply_control_enable+0x804/0xb00 kernel/cgroup/cgroup.c:3212
cgroup_mkdir+0xc67/0xe60 kernel/cgroup/cgroup.c:5608
kernfs_iop_mkdir+0x24c/0x3d0 fs/kernfs/dir.c:1175
vfs_mkdir+0x387/0x570 fs/namei.c:4073
do_mkdirat+0x1d7/0x5a0 fs/namei.c:4098
__do_sys_mkdirat fs/namei.c:4113 [inline]
__se_sys_mkdirat fs/namei.c:4111 [inline]
__x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1340 [inline]
free_pcp_prepare mm/page_alloc.c:1391 [inline]
free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
free_unref_page+0x94/0x280 mm/page_alloc.c:3396
qlist_free_all+0x35/0x90 mm/kasan/quarantine.c:176
kasan_quarantine_reduce+0x150/0x160 mm/kasan/quarantine.c:283
__kasan_slab_alloc+0x2f/0xd0 mm/kasan/common.c:444
kasan_slab_alloc include/linux/kasan.h:254 [inline]
slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
slab_alloc_node mm/slub.c:3225 [inline]
slab_alloc mm/slub.c:3233 [inline]
kmem_cache_alloc+0x100/0x290 mm/slub.c:3238
getname_flags+0xb5/0x500 fs/namei.c:138
do_sys_openat2+0xcf/0x4a0 fs/open.c:1249
do_sys_open fs/open.c:1271 [inline]
__do_sys_openat fs/open.c:1287 [inline]
__se_sys_openat fs/open.c:1282 [inline]
__x64_sys_openat+0x135/0x160 fs/open.c:1282
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0

Memory state around the buggy address:
ffff88814635a700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88814635a780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88814635a800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88814635a880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88814635a900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: 00 9c 8f 84 24 80 00 add %bl,0x802484(%rdi,%rcx,4)
7: 00 00 add %al,(%rax)
9: f6 84 24 81 00 00 00 testb $0x2,0x81(%rsp)
10: 02
11: 0f 85 f6 00 00 00 jne 0x10d
17: 41 f7 c6 00 02 00 00 test $0x200,%r14d
1e: 74 01 je 0x21
20: fb sti
21: 48 c7 44 24 60 0e 36 movq $0x45e0360e,0x60(%rsp)
28: e0 45
* 2a: 4b c7 44 3d 00 00 00 movq $0x0,0x0(%r13,%r15,1) <-- trapping instruction
31: 00 00
33: 66 43 c7 44 3d 09 00 movw $0x0,0x9(%r13,%r15,1)
3a: 00
3b: 43 rex.XB
3c: c6 .byte 0xc6
3d: 44 rex.R
3e: 3d .byte 0x3d
3f: 0b .byte 0xb


---
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