==================================================================
BUG: KASAN: use-after-free in strlen+0x57/0x70 lib/string.c:502
Read of size 1 at addr ffff88810e5d4400 by task kworker/u4:4/314

CPU: 0 PID: 314 Comm: kworker/u4:4 Tainted: G S                 syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: ext4-rsv-conversion ext4_end_io_rsv_work

Call Trace:
 <IRQ>
 __dump_stack+0x21/0x24 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 print_address_description+0x71/0x200 mm/kasan/report.c:316
 print_report+0x4a/0x60 mm/kasan/report.c:420
 kasan_report+0x122/0x150 mm/kasan/report.c:524
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report_generic.c:348
 strlen+0x57/0x70 lib/string.c:502
 __fortify_strlen include/linux/fortify-string.h:196 [inline]
 usb_gadget_get_string+0x1a9/0x310 drivers/usb/gadget/usbstring.c:58
 lookup_string drivers/usb/gadget/composite.c:1172 [inline]
 get_string+0x467/0x1560 drivers/usb/gadget/composite.c:1249
 composite_setup+0x17ac/0x2950 drivers/usb/gadget/composite.c:1780
 android_setup+0x257/0x3a0 drivers/usb/gadget/configfs.c:1580
 dummy_timer+0x1310/0x3270 drivers/usb/gadget/udc/dummy_hcd.c:1936
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x398/0x890 kernel/time/hrtimer.c:1749
 hrtimer_run_softirq+0x19b/0x260 kernel/time/hrtimer.c:1766
 handle_softirqs+0x1d7/0x600 kernel/softirq.c:642
 __do_softirq kernel/softirq.c:680 [inline]
 invoke_softirq kernel/softirq.c:497 [inline]
 __irq_exit_rcu+0x52/0xf0 kernel/softirq.c:729
 irq_exit_rcu+0x9/0x10 kernel/softirq.c:741
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa9/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x55/0x80 kernel/locking/spinlock.c:194
Code: 80 db 0d 87 e8 7c f1 b5 fc 4c 89 f7 48 83 3d 01 dc 0c 02 00 74 30 e8 9e 0d 00 00 90 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> d6 96 4b fc 65 8b 05 27 6e 01 7b 85 c0 74 05 5b 41 5e 5d c3 e8
RSP: 0018:ffffc9000dc3fb18 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000a06 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000a06 RDI: 0000000000000001
RBP: ffffc9000dc3fb28 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52001b87f3c R12: 0000000000000000
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000000
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 ext4_finish_bio+0x637/0x750 fs/ext4/page-io.c:142
 ext4_release_io_end+0xf2/0x2c0 fs/ext4/page-io.c:160
 ext4_end_io_end fs/ext4/page-io.c:194 [inline]
 ext4_do_flush_completed_IO fs/ext4/page-io.c:259 [inline]
 ext4_end_io_rsv_work+0x50d/0x620 fs/ext4/page-io.c:273
 process_one_work+0x717/0xc30 kernel/workqueue.c:2302
 worker_thread+0xa4d/0x11d0 kernel/workqueue.c:2449
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Allocated by task 316:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_alloc_info+0x1f/0x30 mm/kasan/generic.c:505
 ____kasan_kmalloc mm/kasan/common.c:380 [inline]
 __kasan_kmalloc+0x95/0xb0 mm/kasan/common.c:389
 kasan_kmalloc include/linux/kasan.h:212 [inline]
 kmalloc_trace+0x40/0xb0 mm/slab_common.c:1033
 kmalloc include/linux/slab.h:563 [inline]
 usb_string_copy drivers/usb/gadget/configfs.c:155 [inline]
 gadget_strings_product_store+0xeb/0x1f0 drivers/usb/gadget/configfs.c:804
 flush_write_buffer fs/configfs/file.c:207 [inline]
 configfs_write_iter+0x323/0x410 fs/configfs/file.c:229
 call_write_iter include/linux/fs.h:2282 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x5ef/0xd00 fs/read_write.c:584
 ksys_write+0x14a/0x260 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x7b/0x90 fs/read_write.c:646
 x64_sys_call+0x27b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 334:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x132/0x180 mm/kasan/common.c:242
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:250
 kasan_slab_free include/linux/kasan.h:178 [inline]
 slab_free_hook mm/slub.c:1750 [inline]
 slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1776
 slab_free mm/slub.c:3712 [inline]
 __kmem_cache_free+0xb7/0x1b0 mm/slub.c:3728
 kfree+0x6f/0xf0 mm/slab_common.c:990
 gadget_strings_attr_release+0x5f/0x190 drivers/usb/gadget/configfs.c:819
 config_item_cleanup fs/configfs/item.c:128 [inline]
 config_item_release fs/configfs/item.c:137 [inline]
 kref_put include/linux/kref.h:65 [inline]
 config_item_put+0x166/0x210 fs/configfs/item.c:149
 configfs_rmdir+0x8c9/0x980 fs/configfs/dir.c:1540
 vfs_rmdir+0x381/0x4f0 fs/namei.c:4198
 do_rmdir+0x261/0x6b0 fs/namei.c:4259
 __do_sys_rmdir fs/namei.c:4278 [inline]
 __se_sys_rmdir fs/namei.c:4276 [inline]
 __x64_sys_rmdir+0x49/0x50 fs/namei.c:4276
 x64_sys_call+0x68e/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:85
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff88810e5d4400
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 0 bytes inside of
 128-byte region [ffff88810e5d4400, ffff88810e5d4480)

The buggy address belongs to the physical page:
page:ffffea0004397500 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10e5d4
flags: 0x4000000000000200(slab|zone=1)
raw: 4000000000000200 0000000000000000 dead000000000001 ffff888100042a80
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 1, tgid 1 (swapper/0), ts 2699551204, free_ts 0
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2672
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2679
 get_page_from_freelist+0x2ca9/0x2d20 mm/page_alloc.c:4586
 __alloc_pages+0x1fa/0x610 mm/page_alloc.c:5930
 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1
 allocate_slab mm/slub.c:1967 [inline]
 new_slab+0x98/0x3e0 mm/slub.c:2020
 ___slab_alloc+0x70f/0xb70 mm/slub.c:3177
 __slab_alloc+0x5e/0xa0 mm/slub.c:3263
 slab_alloc_node mm/slub.c:3348 [inline]
 __kmem_cache_alloc_node+0x204/0x2d0 mm/slub.c:3423
 kmalloc_trace+0x29/0xb0 mm/slab_common.c:1028
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 call_usermodehelper_setup+0x8e/0x210 kernel/umh.c:366
 kobject_uevent_env+0x650/0x720 lib/kobject_uevent.c:629
 kobject_uevent+0x1d/0x30 lib/kobject_uevent.c:657
 device_add+0xa1a/0xec0 drivers/base/core.c:3679
 usb_add_gadget+0x330/0x620 drivers/usb/gadget/udc/core.c:1415
 usb_add_gadget_udc_release drivers/usb/gadget/udc/core.c:1478 [inline]
 usb_add_gadget_udc+0x11a/0x150 drivers/usb/gadget/udc/core.c:1525
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88810e5d4300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88810e5d4380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88810e5d4400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88810e5d4480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88810e5d4500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
   0:	80 db 0d             	sbb    $0xd,%bl
   3:	87 e8                	xchg   %ebp,%eax
   5:	7c f1                	jl     0xfffffff8
   7:	b5 fc                	mov    $0xfc,%ch
   9:	4c 89 f7             	mov    %r14,%rdi
   c:	48 83 3d 01 dc 0c 02 	cmpq   $0x0,0x20cdc01(%rip)        # 0x20cdc15
  13:	00
  14:	74 30                	je     0x46
  16:	e8 9e 0d 00 00       	call   0xdb9
  1b:	90                   	nop
  1c:	f7 c3 00 02 00 00    	test   $0x200,%ebx
  22:	74 01                	je     0x25
  24:	fb                   	sti
  25:	bf 01 00 00 00       	mov    $0x1,%edi
* 2a:	e8 d6 96 4b fc       	call   0xfc4b9705 <-- trapping instruction
  2f:	65 8b 05 27 6e 01 7b 	mov    %gs:0x7b016e27(%rip),%eax        # 0x7b016e5d
  36:	85 c0                	test   %eax,%eax
  38:	74 05                	je     0x3f
  3a:	5b                   	pop    %rbx
  3b:	41 5e                	pop    %r14
  3d:	5d                   	pop    %rbp
  3e:	c3                   	ret
  3f:	e8                   	.byte 0xe8