Re: [syzbot] [usb?] KASAN: slab-use-after-free Write in usb_giveback_urb_bh

[Aleksandr Nogikh]

#syz invalid

See the discussion at
https://lore.kernel.org/all/6a88012e.dbb3a75c.13dd47.0007.GAE@xxxxxxxxxx/T/

On Sat, Aug 22, 2026 at 9:43 PM syzbot
<syzbot+cade843a1e4af0651f5e@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    a4ff2be345d0 Merge tag 'v7.3-p1' of git://git.kernel.org/p..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1723ee79580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=2823969bbc36a8c4
> dashboard link: https://syzkaller.appspot.com/bug?extid=cade843a1e4af0651f5e
> 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/058e33081021/disk-a4ff2be3.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/33ebad2a63ba/vmlinux-a4ff2be3.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/6e7b43fa415b/bzImage-a4ff2be3.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+cade843a1e4af0651f5e@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> ==================================================================
> BUG: KASAN: slab-use-after-free in usb_giveback_urb_bh+0x2b9/0x440 drivers/usb/core/hcd.c:1692
> Write of size 8 at addr ffff888029ab0338 by task ksoftirqd/0/15
>
> CPU: 0 UID: 0 PID: 15 Comm: ksoftirqd/0 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)}
> Tainted: [L]=SOFTLOCKUP
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
>  print_address_description+0x55/0x1e0 mm/kasan/report.c:378
>  print_report+0x58/0x70 mm/kasan/report.c:482
>  kasan_report+0x117/0x150 mm/kasan/report.c:595
>  usb_giveback_urb_bh+0x2b9/0x440 drivers/usb/core/hcd.c:1692
>  process_one_work kernel/workqueue.c:3322 [inline]
>  process_scheduled_works+0xa88/0x14c0 kernel/workqueue.c:3405
>  bh_worker+0x46a/0x880 kernel/workqueue.c:3708
>  tasklet_hi_action+0xf/0x70 kernel/softirq.c:1003
>  handle_softirqs+0x1da/0x6d0 kernel/softirq.c:645
>  run_ksoftirqd+0x53/0x190 kernel/softirq.c:1108
>  smpboot_thread_fn+0x565/0xa70 kernel/smpboot.c:160
>  kthread+0x38b/0x470 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>
>
> 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:5334 [inline]
>  __kmalloc_noprof+0x422/0x780 mm/slub.c:5359
>  _kmalloc_noprof include/linux/slab.h:992 [inline]
>  _kzalloc_noprof include/linux/slab.h:1309 [inline]
>  __usb_create_hcd+0x67/0x900 drivers/usb/core/hcd.c:2566
>  dummy_hcd_probe+0xf6/0x270 drivers/usb/gadget/udc/dummy_hcd.c:2717
>  platform_probe+0xf9/0x190 drivers/base/platform.c:1507
>  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
>  driver_probe_device+0x4f/0x240 drivers/base/dd.c:898
>  __device_attach_driver+0x270/0x410 drivers/base/dd.c:1026
>  bus_for_each_drv+0x25b/0x2f0 drivers/base/bus.c:500
>  __device_attach+0x2c7/0x450 drivers/base/dd.c:1098
>  device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1153
>  bus_probe_device+0x12d/0x220 drivers/base/bus.c:620
>  device_add+0x7d7/0xb80 drivers/base/core.c:3776
>  platform_device_add+0x4bd/0x860 drivers/base/platform.c:833
>  dummy_hcd_init+0x667/0xd00 drivers/usb/gadget/udc/dummy_hcd.c:2873
>  do_one_initcall+0x250/0x870 init/main.c:1353
>  do_initcall_level+0x10a/0x1a0 init/main.c:1415
>  do_initcalls+0x59/0xa0 init/main.c:1431
>  kernel_init_freeable+0x29d/0x3e0 init/main.c:1666
>  kernel_init+0x22/0x1d0 init/main.c:1556
>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>
> Freed by task 8989:
>  kasan_save_stack mm/kasan/common.c:57 [inline]
>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
>  kasan_save_free_info+0x40/0x50 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:2677 [inline]
>  slab_free mm/slub.c:6377 [inline]
>  kfree+0x1c5/0x6d0 mm/slub.c:6692
>  usb_release_dev+0x57/0xe0 drivers/usb/core/usb.c:497
>  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
>  usbdev_open+0x1f0/0x790 drivers/usb/core/devio.c:1086
>  chrdev_open+0x4dc/0x600 fs/char_dev.c:411
>  do_dentry_open+0x849/0x1420 fs/open.c:996
>  vfs_open+0x3b/0x350 fs/open.c:1101
>  do_open fs/namei.c:4837 [inline]
>  path_openat+0x1448/0x1d60 fs/namei.c:5000
>  do_file_open+0x23e/0x4a0 fs/namei.c:5029
>  do_sys_openat2+0x115/0x200 fs/open.c:1417
>  do_sys_open fs/open.c:1423 [inline]
>  __do_sys_openat fs/open.c:1439 [inline]
>  __se_sys_openat fs/open.c:1434 [inline]
>  __x64_sys_openat+0x138/0x170 fs/open.c:1434
>  do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
>  do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> 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:2226
>  __queue_work+0xd1e/0x10f0 kernel/workqueue.c:2401
>  queue_work_on+0x106/0x1d0 kernel/workqueue.c:2452
>  usb_rh_urb_dequeue drivers/usb/core/hcd.c:845 [inline]
>  unlink1+0x33d/0x3e0 drivers/usb/core/hcd.c:1580
>  usb_hcd_flush_endpoint+0x167/0x440 drivers/usb/core/hcd.c:1794
>  usb_disable_endpoint drivers/usb/core/message.c:1362 [inline]
>  usb_disable_interface+0x279/0x350 drivers/usb/core/message.c:1408
>  usb_unbind_interface+0x265/0x9f0 drivers/usb/core/driver.c:456
>  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+0x449/0x560 drivers/base/bus.c:664
>  device_del+0x528/0x8f0 drivers/base/core.c:3965
>  usb_disable_device+0x3d4/0x8d0 drivers/usb/core/message.c:1478
>  usb_disconnect+0x32d/0x990 drivers/usb/core/hub.c:2345
>  usb_remove_hcd+0x275/0x670 drivers/usb/core/hcd.c:3059
>  dummy_hcd_remove+0xed/0x130 drivers/usb/gadget/udc/dummy_hcd.c:2761
>  device_remove drivers/base/dd.c:616 [inline]
>  __device_release_driver drivers/base/dd.c:1349 [inline]
>  device_release_driver_internal+0x48b/0x880 drivers/base/dd.c:1372
>  unbind_store+0x1a4/0x1d0 drivers/base/bus.c:244
>  kernfs_fop_write_iter+0x3a5/0x540 fs/kernfs/file.c:345
>  new_sync_write fs/read_write.c:595 [inline]
>  vfs_write+0x61e/0xbb0 fs/read_write.c:687
>  ksys_write+0x156/0x270 fs/read_write.c:739
>  do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
>  do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> 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:2226
>  __queue_work+0xd1e/0x10f0 kernel/workqueue.c:2401
>  queue_work_on+0x106/0x1d0 kernel/workqueue.c:2452
>  rh_call_control drivers/usb/core/hcd.c:706 [inline]
>  rh_urb_enqueue drivers/usb/core/hcd.c:817 [inline]
>  usb_hcd_submit_urb+0xa2d/0x1b40 drivers/usb/core/hcd.c:1538
>  usb_start_wait_urb+0x13f/0x5b0 drivers/usb/core/message.c:62
>  usb_internal_control_msg drivers/usb/core/message.c:117 [inline]
>  usb_control_msg+0x234/0x3e0 drivers/usb/core/message.c:167
>  usb_clear_port_feature drivers/usb/core/hub.c:456 [inline]
>  port_event drivers/usb/core/hub.c:5773 [inline]
>  hub_event+0x832/0x4cf0 drivers/usb/core/hub.c:5961
>  process_one_work kernel/workqueue.c:3322 [inline]
>  process_scheduled_works+0xa88/0x14c0 kernel/workqueue.c:3405
>  worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
>  kthread+0x38b/0x470 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
>
> The buggy address belongs to the object at ffff888029ab0000
>  which belongs to the cache kmalloc-2k of size 2048
> The buggy address is located 824 bytes inside of
>  freed 2048-byte region [ffff888029ab0000, ffff888029ab0800)
>
> The buggy address belongs to the physical page:
> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888029ab6000 pfn:0x29ab0
> head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
> flags: 0x80000000000240(workingset|head|node=0|zone=1)
> page_type: f5(slab)
> raw: 0080000000000240 ffff88813ffb2000 ffffea0000a7ce10 ffffea0000a55a10
> raw: ffff888029ab6000 0000000800080006 00000000f5000000 0000000000000000
> head: 0080000000000240 ffff88813ffb2000 ffffea0000a7ce10 ffffea0000a55a10
> head: ffff888029ab6000 0000000800080006 00000000f5000000 0000000000000000
> head: 0080000000000003 fffffffffffffe01 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 12235747769, free_ts 11878976125
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1859
>  prep_new_page mm/page_alloc.c:1867 [inline]
>  get_page_from_freelist+0x2630/0x26a0 mm/page_alloc.c:3946
>  __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5304
>  alloc_slab_page mm/slub.c:3266 [inline]
>  allocate_slab+0x79/0x5e0 mm/slub.c:3380
>  new_slab mm/slub.c:3426 [inline]
>  refill_objects+0x2d8/0x350 mm/slub.c:7310
>  refill_sheaf mm/slub.c:2804 [inline]
>  __pcs_replace_empty_main+0x334/0x690 mm/slub.c:4675
>  alloc_from_pcs mm/slub.c:4773 [inline]
>  slab_alloc_node mm/slub.c:4905 [inline]
>  __do_kmalloc_node mm/slub.c:5333 [inline]
>  __kmalloc_noprof+0x54c/0x780 mm/slub.c:5359
>  _kmalloc_noprof include/linux/slab.h:992 [inline]
>  _kzalloc_noprof include/linux/slab.h:1309 [inline]
>  platform_device_alloc+0x39/0x260 drivers/base/platform.c:634
>  dummy_hcd_init+0x2c9/0xd00 drivers/usb/gadget/udc/dummy_hcd.c:2841
>  do_one_initcall+0x250/0x870 init/main.c:1353
>  do_initcall_level+0x10a/0x1a0 init/main.c:1415
>  do_initcalls+0x59/0xa0 init/main.c:1431
>  kernel_init_freeable+0x29d/0x3e0 init/main.c:1666
>  kernel_init+0x22/0x1d0 init/main.c:1556
>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
> page last free pid 100 tgid 100 stack trace:
>  reset_page_owner include/linux/page_owner.h:25 [inline]
>  __free_pages_prepare mm/page_alloc.c:1406 [inline]
>  free_pages_prepare+0x946/0xa40 mm/page_alloc.c:1451
>  __free_contig_range_common+0x174/0x340 mm/page_alloc.c:6897
>  __free_contig_range mm/page_alloc.c:6942 [inline]
>  free_pages_bulk+0x48/0x120 mm/page_alloc.c:5257
>  vm_area_free_pages mm/vmalloc.c:3461 [inline]
>  vfree+0x26d/0x510 mm/vmalloc.c:3510
>  delayed_vfree_work+0x55/0x80 mm/vmalloc.c:3414
>  process_one_work kernel/workqueue.c:3322 [inline]
>  process_scheduled_works+0xa88/0x14c0 kernel/workqueue.c:3405
>  worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
>  kthread+0x38b/0x470 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
>
> Memory state around the buggy address:
>  ffff888029ab0200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff888029ab0280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >ffff888029ab0300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                                         ^
>  ffff888029ab0380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff888029ab0400: 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@xxxxxxxxxxxxxxxx.
>
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>
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