Message-ID: <696f6807.050a0220.4cb9c.0010.GAE@google.com>
Date: Tue, 20 Jan 2026 03:33:27 -0800
From: syzbot <syzbot+62c1aa73226b3ac3b107@...kaller.appspotmail.com>
To: gregkh@...uxfoundation.org, i@...ithal.me, linux-kernel@...r.kernel.org, 
	linux-usb@...r.kernel.org, shuah@...nel.org, syzkaller-bugs@...glegroups.com, 
	valentina.manea.m@...il.com
Subject: [syzbot] [usb?] KASAN: slab-use-after-free Read in event_handler

Hello,

syzbot found the following issue on:

HEAD commit:    24d479d26b25 Linux 6.19-rc6
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12d11852580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c33bf4a3a0c7a4f1
dashboard link: https://syzkaller.appspot.com/bug?extid=62c1aa73226b3ac3b107
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f0555f920605/disk-24d479d2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ae277d28fcd2/vmlinux-24d479d2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b4f8db4a51a6/bzImage-24d479d2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+62c1aa73226b3ac3b107@...kaller.appspotmail.com

vhci_hcd vhci_hcd.15: stop threads
vhci_hcd vhci_hcd.15: release socket
vhci_hcd vhci_hcd.15: disconnect device
vhci_hcd vhci_hcd.15: stop threads
vhci_hcd vhci_hcd.15: relea[   23.071571][   T13] vhci_hcd vhci_hcd.15: release socket
vhci_hcd vhci_hcd.15: disconnect device
vhci_hcd vhci_hcd.15: stop threads
vhci_hcd vhci_hcd.15: release socket
vhci_hcd vhci_hcd.15: disconnect device
vhci_hcd vhci_hcd.15: stop threads
vhci_hcd vhci_hcd.15: release socket
vhci_hcd vhci_hcd.15: disconnect device
vhci_hcd vhci_hcd.15: stop threads
vhci_hcd vhci_hcd.15: release socket
vhci_hcd vhci_hcd.15: disconnect device
vhci_hcd vhci_hcd.15: stop threads
vhci_hcd vhci_hcd.15: release socket
vhci_hcd vhci_hcd.15: disconnect device
vhci_hcd vhci_hcd.15: stop threads
vhci_hcd vhci_hcd.15: release socket
vhci_hcd vhci_hcd.15: disconnect device
vhci_hcd vhci_hcd.15: stop threads
vhci_hcd vhci_hcd.15: release socket
vhci_hcd vhci_hcd.15: disconnect device
==================================================================
BUG: KASAN: slab-use-after-free in __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:162
Read of size 1 at addr ffff8881477add10 by task kworker/u8:1/13

CPU: 0 UID: 0 PID: 13 Comm: kworker/u8:1 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: usbip_event event_handler
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 __kasan_check_byte+0x2a/0x40 mm/kasan/common.c:574
 kasan_check_byte include/linux/kasan.h:402 [inline]
 lock_acquire+0x84/0x330 kernel/locking/lockdep.c:5842
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:162
 rt_mutex_slowunlock+0xbf/0x8b0 kernel/locking/rtmutex.c:1417
 spin_unlock_irqrestore include/linux/spinlock_rt.h:122 [inline]
 __wake_up_common_lock+0x18a/0x1e0 kernel/sched/wait.c:127
 event_handler+0x3cb/0x4b0 drivers/usb/usbip/usbip_event.c:96
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3340
 worker_thread+0x89f/0xd90 kernel/workqueue.c:3421
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>

Allocated by task 1:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5657 [inline]
 __kmalloc_noprof+0x235/0x7c0 mm/slub.c:5669
 kmalloc_noprof include/linux/slab.h:961 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 __usb_create_hcd+0x67/0x920 drivers/usb/core/hcd.c:2570
 vhci_hcd_probe+0x104/0x3f0 drivers/usb/usbip/vhci_hcd.c:1378
 platform_probe+0xf9/0x190 drivers/base/platform.c:1446
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x26d/0xac0 drivers/base/dd.c:659
 __driver_probe_device+0x18c/0x320 drivers/base/dd.c:801
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:831
 __device_attach_driver+0x279/0x430 drivers/base/dd.c:959
 bus_for_each_drv+0x25b/0x2f0 drivers/base/bus.c:500
 __device_attach+0x2c8/0x450 drivers/base/dd.c:1031
 device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1086
 bus_probe_device+0x12d/0x220 drivers/base/bus.c:574
 device_add+0x7b6/0xb80 drivers/base/core.c:3689
 platform_device_add+0x46a/0x800 drivers/base/platform.c:757
 platform_device_register_full+0x46c/0x570 drivers/base/platform.c:885
 vhci_hcd_init+0x1e9/0x390 drivers/usb/usbip/vhci_hcd.c:1557
 do_one_initcall+0x250/0x840 init/main.c:1378
 do_initcall_level+0x104/0x190 init/main.c:1440
 do_initcalls+0x59/0xa0 init/main.c:1456
 kernel_init_freeable+0x2a6/0x3d0 init/main.c:1688
 kernel_init+0x1d/0x1d0 init/main.c:1578
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

Freed by task 1:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2540 [inline]
 slab_free mm/slub.c:6670 [inline]
 kfree+0x1bb/0x8f0 mm/slub.c:6878
 vhci_hcd_probe+0x258/0x3f0 drivers/usb/usbip/vhci_hcd.c:1415
 platform_probe+0xf9/0x190 drivers/base/platform.c:1446
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x26d/0xac0 drivers/base/dd.c:659
 __driver_probe_device+0x18c/0x320 drivers/base/dd.c:801
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:831
 __device_attach_driver+0x279/0x430 drivers/base/dd.c:959
 bus_for_each_drv+0x25b/0x2f0 drivers/base/bus.c:500
 __device_attach+0x2c8/0x450 drivers/base/dd.c:1031
 device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1086
 bus_probe_device+0x12d/0x220 drivers/base/bus.c:574
 device_add+0x7b6/0xb80 drivers/base/core.c:3689
 platform_device_add+0x46a/0x800 drivers/base/platform.c:757
 platform_device_register_full+0x46c/0x570 drivers/base/platform.c:885
 vhci_hcd_init+0x1e9/0x390 drivers/usb/usbip/vhci_hcd.c:1557
 do_one_initcall+0x250/0x840 init/main.c:1378
 do_initcall_level+0x104/0x190 init/main.c:1440
 do_initcalls+0x59/0xa0 init/main.c:1456
 kernel_init_freeable+0x2a6/0x3d0 init/main.c:1688
 kernel_init+0x1d/0x1d0 init/main.c:1578
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 insert_work+0x3d/0x330 kernel/workqueue.c:2180
 __queue_work+0xcfd/0xff0 kernel/workqueue.c:2335
 queue_work_on+0x106/0x1c0 kernel/workqueue.c:2386
 usb_rh_urb_dequeue drivers/usb/core/hcd.c:849 [inline]
 unlink1+0x34c/0x3f0 drivers/usb/core/hcd.c:1584
 usb_hcd_unlink_urb+0xda/0x1d0 drivers/usb/core/hcd.c:1621
 usb_kill_urb+0x10b/0x2f0 drivers/usb/core/urb.c:717
 hub_quiesce+0x210/0x320 drivers/usb/core/hub.c:1412
 hub_suspend+0x7e8/0x9b0 drivers/usb/core/hub.c:4008
 usb_suspend_interface drivers/usb/core/driver.c:1323 [inline]
 usb_suspend_both+0x31f/0x1310 drivers/usb/core/driver.c:1445
 usb_runtime_suspend+0x58/0x110 drivers/usb/core/driver.c:1997
 __rpm_callback+0x2be/0x7a0 drivers/base/power/runtime.c:406
 rpm_callback drivers/base/power/runtime.c:460 [inline]
 rpm_suspend+0x87d/0x16e0 drivers/base/power/runtime.c:698
 __pm_runtime_suspend+0x12c/0x1a0 drivers/base/power/runtime.c:1167
 pm_runtime_autosuspend include/linux/pm_runtime.h:415 [inline]
 usb_runtime_idle+0x76/0x90 drivers/usb/core/driver.c:2034
 rpm_idle+0x383/0x8d0 drivers/base/power/runtime.c:550
 pm_runtime_work+0x11e/0x1b0 drivers/base/power/runtime.c:995
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3340
 worker_thread+0x89f/0xd90 kernel/workqueue.c:3421
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

Second to last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 insert_work+0x3d/0x330 kernel/workqueue.c:2180
 __queue_work+0xcfd/0xff0 kernel/workqueue.c:2335
 queue_work_on+0x106/0x1c0 kernel/workqueue.c:2386
 rh_call_control drivers/usb/core/hcd.c:711 [inline]
 rh_urb_enqueue drivers/usb/core/hcd.c:821 [inline]
 usb_hcd_submit_urb+0x11db/0x1b50 drivers/usb/core/hcd.c:1542
 usb_start_wait_urb+0x12b/0x510 drivers/usb/core/message.c:59
 usb_internal_control_msg drivers/usb/core/message.c:103 [inline]
 usb_control_msg+0x232/0x3e0 drivers/usb/core/message.c:154
 get_port_status drivers/usb/core/hub.c:607 [inline]
 hub_ext_port_status+0x116/0x820 drivers/usb/core/hub.c:624
 usb_hub_port_status drivers/usb/core/hub.c:674 [inline]
 hub_activate+0x6eb/0x1a80 drivers/usb/core/hub.c:1185
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3340
 worker_thread+0x89f/0xd90 kernel/workqueue.c:3421
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

The buggy address belongs to the object at ffff8881477ac000
 which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 7440 bytes inside of
 freed 8192-byte region [ffff8881477ac000, ffff8881477ae000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1477a8
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x500000000000040(head|node=1|zone=2)
page_type: f5(slab)
raw: 0500000000000040 ffff88813fe27280 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000020002 00000000f5000000 0000000000000000
head: 0500000000000040 ffff88813fe27280 dead000000000122 0000000000000000
head: 0000000000000000 0000000000020002 00000000f5000000 0000000000000000
head: 0500000000000003 ffffea00051dea01 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000008
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, tgid 1 (swapper/0), ts 22636347125, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x228/0x280 mm/page_alloc.c:1884
 prep_new_page mm/page_alloc.c:1892 [inline]
 get_page_from_freelist+0x28bb/0x2950 mm/page_alloc.c:3945
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5240
 alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2486
 alloc_slab_page mm/slub.c:3075 [inline]
 allocate_slab+0x86/0x3a0 mm/slub.c:3248
 new_slab mm/slub.c:3302 [inline]
 ___slab_alloc+0xaf8/0x13d0 mm/slub.c:4656
 __slab_alloc+0xc5/0x1f0 mm/slub.c:4779
 __slab_alloc_node mm/slub.c:4855 [inline]
 slab_alloc_node mm/slub.c:5251 [inline]
 __do_kmalloc_node mm/slub.c:5656 [inline]
 __kmalloc_noprof+0x15e/0x7c0 mm/slub.c:5669
 kmalloc_noprof include/linux/slab.h:961 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 __usb_create_hcd+0x67/0x920 drivers/usb/core/hcd.c:2570
 vhci_hcd_probe+0x1e6/0x3f0 drivers/usb/usbip/vhci_hcd.c:1394
 platform_probe+0xf9/0x190 drivers/base/platform.c:1446
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x26d/0xac0 drivers/base/dd.c:659
 __driver_probe_device+0x18c/0x320 drivers/base/dd.c:801
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:831
 __device_attach_driver+0x279/0x430 drivers/base/dd.c:959
 bus_for_each_drv+0x25b/0x2f0 drivers/base/bus.c:500
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8881477adc00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881477adc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881477add00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff8881477add80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881477ade00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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@...glegroups.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

Powered by blists - more mailing lists