KASAN: use-after-free Read in gadget_dev_open

Status: upstream: reported C repro on 2026/08/25 18:30
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+19e6f456f82a3df0888a@syzkaller.appspotmail.com
First crash: 20d, last: 6d08h
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/09/08 linux-6.1.y (ToT) cf82dcca9634 C [report] KASAN: use-after-free Read in gadget_dev_open
2026/09/08 upstream (ToT) 5acbae5f7eb3 C Didn't crash
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Read in gadget_dev_open prio:normal usb 19 syz, C 183 21h17m 45d 0/29 upstream: reported C repro on 2026/07/31 06:03

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x104/0x6634 kernel/locking/lockdep.c:4933
Read of size 8 at addr ffff0000deb98818 by task syz.0.18/4464

CPU: 0 PID: 4464 Comm: syz.0.18 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
Call trace:
 dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106
 print_address_description+0x88/0x218 mm/kasan/report.c:316
 print_report+0x50/0x68 mm/kasan/report.c:420
 kasan_report+0xa8/0xfc mm/kasan/report.c:524
 __asan_report_load8_noabort+0x2c/0x38 mm/kasan/report_generic.c:351
 __lock_acquire+0x104/0x6634 kernel/locking/lockdep.c:4933
 lock_acquire+0x20c/0x638 kernel/locking/lockdep.c:5676
 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
 _raw_spin_lock_irq+0x70/0x98 kernel/locking/spinlock.c:170
 spin_lock_irq include/linux/spinlock.h:376 [inline]
 gadget_dev_open+0x50/0x1c4 drivers/usb/gadget/legacy/inode.c:1914
 do_dentry_open+0x738/0xf8c fs/open.c:882
 vfs_open+0x7c/0x90 fs/open.c:1015
 do_open fs/namei.c:3677 [inline]
 path_openat+0x1fc0/0x27a0 fs/namei.c:3834
 do_filp_open+0x198/0x38c fs/namei.c:3861
 do_sys_openat2+0x134/0x3fc fs/open.c:1320
 do_sys_open fs/open.c:1336 [inline]
 __do_sys_openat fs/open.c:1352 [inline]
 __se_sys_openat fs/open.c:1347 [inline]
 __arm64_sys_openat+0x11c/0x150 fs/open.c:1347
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Allocated by task 4438:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:53
 kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:505
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0xa0/0xb8 mm/kasan/common.c:384
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 kmalloc_trace+0x7c/0x94 mm/slab_common.c:1031
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 dev_new drivers/usb/gadget/legacy/inode.c:170 [inline]
 gadgetfs_fill_super+0x2c0/0x5c0 drivers/usb/gadget/legacy/inode.c:2049
 vfs_get_super fs/super.c:1222 [inline]
 get_tree_single+0xb8/0x170 fs/super.c:1260
 gadgetfs_get_tree+0x28/0x38 drivers/usb/gadget/legacy/inode.c:2080
 vfs_get_tree+0x90/0x278 fs/super.c:1584
 do_new_mount+0x228/0x804 fs/namespace.c:3078
 path_mount+0x5ac/0xe6c fs/namespace.c:3408
 do_mount fs/namespace.c:3421 [inline]
 __do_sys_mount fs/namespace.c:3629 [inline]
 __se_sys_mount fs/namespace.c:3606 [inline]
 __arm64_sys_mount+0x4a0/0x5a0 fs/namespace.c:3606
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Freed by task 4463:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:53
 kasan_save_free_info+0x38/0x5c mm/kasan/generic.c:516
 ____kasan_slab_free+0x148/0x1b0 mm/kasan/common.c:237
 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:245
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x16c/0x1e8 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xbc/0x21c mm/slub.c:3700
 kfree+0xd0/0x1a8 mm/slab_common.c:988
 put_dev drivers/usb/gadget/legacy/inode.c:163 [inline]
 dev_release+0x160/0x214 drivers/usb/gadget/legacy/inode.c:1211
 __fput+0x1b4/0x7b0 fs/file_table.c:320
 ____fput+0x20/0x30 fs/file_table.c:348
 task_work_run+0x1f4/0x280 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0x54c/0x19ac kernel/exit.c:887
 do_group_exit+0x198/0x238 kernel/exit.c:1030
 get_signal+0x11f4/0x133c kernel/signal.c:2880
 do_signal arch/arm64/kernel/signal.c:1095 [inline]
 do_notify_resume+0x364/0x2c84 arch/arm64/kernel/signal.c:1148
 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
 el0_svc+0x98/0x128 arch/arm64/kernel/entry-common.c:638
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

The buggy address belongs to the object at ffff0000deb98800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 24 bytes inside of
 1024-byte region [ffff0000deb98800, ffff0000deb98c00)

The buggy address belongs to the physical page:
page:0000000059fc2a5c refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11eb98
head:0000000059fc2a5c order:3 compound_mapcount:0 compound_pincount:0
flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000010200 0000000000000000 dead000000000122 ffff0000c0002780
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000deb98700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff0000deb98780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff0000deb98800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff0000deb98880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff0000deb98900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
================================================================================
UBSAN: array-index-out-of-bounds in kernel/locking/qspinlock.c:131:9
index 12987 is out of range for type 'unsigned long[8]'
CPU: 0 PID: 4464 Comm: syz.0.18 Tainted: G    B              syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
Call trace:
 dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106
 dump_stack+0x1c/0x5c lib/dump_stack.c:113
 ubsan_epilogue+0x14/0x48 lib/ubsan.c:151
 __ubsan_handle_out_of_bounds+0xd0/0xf8 lib/ubsan.c:282
 decode_tail kernel/locking/qspinlock.c:131 [inline]
 queued_spin_lock_slowpath+0x8a8/0xc14 kernel/locking/qspinlock.c:471
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock+0x2f4/0x2f8 kernel/locking/spinlock_debug.c:115
 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:120 [inline]
 _raw_spin_lock_irq+0x78/0x98 kernel/locking/spinlock.c:170
 spin_lock_irq include/linux/spinlock.h:376 [inline]
 gadget_dev_open+0x50/0x1c4 drivers/usb/gadget/legacy/inode.c:1914
 do_dentry_open+0x738/0xf8c fs/open.c:882
 vfs_open+0x7c/0x90 fs/open.c:1015
 do_open fs/namei.c:3677 [inline]
 path_openat+0x1fc0/0x27a0 fs/namei.c:3834
 do_filp_open+0x198/0x38c fs/namei.c:3861
 do_sys_openat2+0x134/0x3fc fs/open.c:1320
 do_sys_open fs/open.c:1336 [inline]
 __do_sys_openat fs/open.c:1352 [inline]
 __se_sys_openat fs/open.c:1347 [inline]
 __arm64_sys_openat+0x11c/0x150 fs/open.c:1347
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
================================================================================
Unable to handle kernel paging request at virtual address ffff8000152fb1b0
KASAN: probably user-memory-access in range [0x00000000a97d8d80-0x00000000a97d8d87]
Mem abort info:
  ESR = 0x0000000096000047
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x07: level 3 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000047
  CM = 0, WnR = 1
swapper pgtable: 4k pages, 48-bit VAs, pgdp=000000020dd3f000
[ffff8000152fb1b0] pgd=100000023ffff003, p4d=100000023ffff003, pud=100000023fffe003, pmd=100000023fff9003, pte=0000000000000000
Internal error: Oops: 0000000096000047 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 4464 Comm: syz.0.18 Tainted: G    B              syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
pstate: 824000c5 (Nzcv daIF +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : queued_spin_lock_slowpath+0x598/0xc14 kernel/locking/qspinlock.c:474
lr : decode_tail kernel/locking/qspinlock.c:131 [inline]
lr : queued_spin_lock_slowpath+0x8a8/0xc14 kernel/locking/qspinlock.c:471
sp : ffff800021597520
x29: ffff8000215975c0 x28: 1fffe00033e72c30 x27: ffff8000152fb1b0
x26: ffff00019f396188 x25: ffff800021597540 x24: 1fffe0001bd73100
x23: dfff800000000000 x22: ffff7000042b2ea8 x21: ffff8000152fb1b0
x20: ffff00019f396180 x19: ffff0000deb98800 x18: 0000000000000000
x17: 3d3d3d3d3d3d3d3d x16: ffff800008195558 x15: 3d3d3d3d3d3d3d3d
x14: ffff700002ff20bc x13: 1ffff00002ff20bc x12: 0000000000000004
x11: ff008000081955dc x10: ffff8000152fb180 x9 : 0000000000000003
x8 : 0000000000000000 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff800021596f78 x4 : ffff800015474e80 x3 : ffff8000081955a4
x2 : 0000000000000001 x1 : 0000000000000004 x0 : ffff00019f396188
Call trace:
 queued_spin_lock_slowpath+0x598/0xc14 kernel/locking/qspinlock.c:477
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock+0x2f4/0x2f8 kernel/locking/spinlock_debug.c:115
 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:120 [inline]
 _raw_spin_lock_irq+0x78/0x98 kernel/locking/spinlock.c:170
 spin_lock_irq include/linux/spinlock.h:376 [inline]
 gadget_dev_open+0x50/0x1c4 drivers/usb/gadget/legacy/inode.c:1914
 do_dentry_open+0x738/0xf8c fs/open.c:882
 vfs_open+0x7c/0x90 fs/open.c:1015
 do_open fs/namei.c:3677 [inline]
 path_openat+0x1fc0/0x27a0 fs/namei.c:3834
 do_filp_open+0x198/0x38c fs/namei.c:3861
 do_sys_openat2+0x134/0x3fc fs/open.c:1320
 do_sys_open fs/open.c:1336 [inline]
 __do_sys_openat fs/open.c:1352 [inline]
 __se_sys_openat fs/open.c:1347 [inline]
 __arm64_sys_openat+0x11c/0x150 fs/open.c:1347
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: aa1503e0 978da72c 91002280 52800081 (f90002b4) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	aa1503e0 	mov	x0, x21
   4:	978da72c 	bl	0xfffffffffe369cb4
   8:	91002280 	add	x0, x20, #0x8
   c:	52800081 	mov	w1, #0x4                   	// #4
* 10:	f90002b4 	str	x20, [x21] <-- trapping instruction

Crashes (22):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/25 20:42 linux-6.1.y 05208478041c a9a1fc32 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/09/08 12:40 linux-6.1.y cf82dcca9634 680aa3e1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/09/08 12:32 linux-6.1.y cf82dcca9634 680aa3e1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/09/01 05:37 linux-6.1.y d64a499eea6b 316d9396 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/09/01 05:37 linux-6.1.y d64a499eea6b 316d9396 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/09/01 05:33 linux-6.1.y d64a499eea6b 316d9396 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/09/01 05:13 linux-6.1.y d64a499eea6b 316d9396 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/08/31 09:59 linux-6.1.y d64a499eea6b 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/08/25 18:41 linux-6.1.y 05208478041c a9a1fc32 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/08/25 18:39 linux-6.1.y 05208478041c a9a1fc32 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/08/25 18:39 linux-6.1.y 05208478041c a9a1fc32 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/08/25 18:38 linux-6.1.y 05208478041c a9a1fc32 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/08/25 18:38 linux-6.1.y 05208478041c a9a1fc32 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/08/25 18:36 linux-6.1.y 05208478041c a9a1fc32 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/08/25 18:36 linux-6.1.y 05208478041c a9a1fc32 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/08/25 18:33 linux-6.1.y 05208478041c a9a1fc32 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/08/25 18:32 linux-6.1.y 05208478041c a9a1fc32 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/08/25 18:31 linux-6.1.y 05208478041c a9a1fc32 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/08/25 18:31 linux-6.1.y 05208478041c a9a1fc32 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/08/25 18:31 linux-6.1.y 05208478041c a9a1fc32 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/08/25 18:29 linux-6.1.y 05208478041c a9a1fc32 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
2026/08/25 18:29 linux-6.1.y 05208478041c a9a1fc32 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in gadget_dev_open
* Struck through repros no longer work on HEAD.