KASAN: slab-use-after-free Read in gadget_dev_open

Status: upstream: reported syz repro on 2026/10/28 09:46
Reported-by: syzbot+f529db1ba499cdf141d7@syzkaller.appspotmail.com
First crash: 4d12h, last: 22h00m
▶ ▼ Similar bugs (2)
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 unreliable 267 1h23m 93d 0/29 upstream: reported C repro on 2026/07/31 06:03
linux-6.1 KASAN: use-after-free Read in gadget_dev_open origin:lts-only 19 syz, C 34 8h02m 68d 0/3 upstream: reported C repro on 2026/08/25 18:30

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in __lock_acquire+0x10d/0x7eb0 kernel/locking/lockdep.c:5036
Read of size 8 at addr ffff88807c5d1818 by task syz.0.18/5977

CPU: 0 PID: 5977 Comm: syz.0.18 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 __lock_acquire+0x10d/0x7eb0 kernel/locking/lockdep.c:5036
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5790
 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
 _raw_spin_lock_irq+0xaf/0xf0 kernel/locking/spinlock.c:170
 spin_lock_irq include/linux/spinlock.h:376 [inline]
 gadget_dev_open+0x4b/0x1b0 drivers/usb/gadget/legacy/inode.c:1910
 do_dentry_open+0x880/0x14b0 fs/open.c:929
 do_open fs/namei.c:3695 [inline]
 path_openat+0x284f/0x3270 fs/namei.c:3856
 do_filp_open+0x1f2/0x430 fs/namei.c:3883
 do_sys_openat2+0x134/0x1d0 fs/open.c:1422
 do_sys_open fs/open.c:1437 [inline]
 __do_sys_openat fs/open.c:1453 [inline]
 __se_sys_openat fs/open.c:1448 [inline]
 __x64_sys_openat+0x139/0x160 fs/open.c:1448
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f498199f559
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f49827e4028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f4981c25fa0 RCX: 00007f498199f559
RDX: 0000000000000002 RSI: 0000200000000140 RDI: ffffffffffffff9c
RBP: 00007f4981a36b50 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000084 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4981c26038 R14: 00007f4981c25fa0 R15: 00007ffd27e14cc8
 </TASK>

Allocated by task 5929:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:384
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 dev_new drivers/usb/gadget/legacy/inode.c:170 [inline]
 gadgetfs_fill_super+0x2ec/0x5f0 drivers/usb/gadget/legacy/inode.c:2044
 vfs_get_super fs/super.c:1357 [inline]
 get_tree_single+0xba/0x140 fs/super.c:1384
 vfs_get_tree+0x8c/0x280 fs/super.c:1775
 do_new_mount+0x24a/0xa60 fs/namespace.c:3412
 do_mount fs/namespace.c:3780 [inline]
 __do_sys_mount fs/namespace.c:3989 [inline]
 __se_sys_mount+0x2e7/0x3d0 fs/namespace.c:3966
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 5974:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522
 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1833 [inline]
 slab_free_freelist_hook+0x154/0x240 mm/slub.c:1859
 slab_free mm/slub.c:3853 [inline]
 __kmem_cache_free+0xba/0x1f0 mm/slub.c:3866
 put_dev drivers/usb/gadget/legacy/inode.c:163 [inline]
 dev_release+0x167/0x200 drivers/usb/gadget/legacy/inode.c:1211
 __fput+0x221/0x940 fs/file_table.c:418
 task_work_run+0x1d4/0x260 kernel/task_work.c:245
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:180
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:213
 __syscall_exit_to_user_mode_work kernel/entry/common.c:294 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:305
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff88807c5d1800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 24 bytes inside of
 freed 1024-byte region [ffff88807c5d1800, ffff88807c5d1c00)

The buggy address belongs to the physical page:
page:ffffea0001f17400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7c5d0
head:ffffea0001f17400 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888018c41dc0 dead000000000122 0000000000000000
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 2974, tgid 2974 (kworker/u4:8), ts 121381042033, free_ts 120636224610
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1582
 prep_new_page mm/page_alloc.c:1589 [inline]
 get_page_from_freelist+0x2181/0x22a0 mm/page_alloc.c:3221
 __alloc_pages+0x1f0/0x460 mm/page_alloc.c:4501
 alloc_slab_page+0x5d/0x180 mm/slub.c:1903
 allocate_slab mm/slub.c:2050 [inline]
 new_slab+0x87/0x2d0 mm/slub.c:2103
 ___slab_alloc+0xc5c/0x12f0 mm/slub.c:3275
 __slab_alloc mm/slub.c:3361 [inline]
 __slab_alloc_node mm/slub.c:3414 [inline]
 slab_alloc_node mm/slub.c:3508 [inline]
 __kmem_cache_alloc_node+0x122/0x260 mm/slub.c:3557
 kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1098
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 cfg80211_ibss_joined+0x15f/0x4d0 net/wireless/ibss.c:72
 __ieee80211_sta_join_ibss+0xc46/0x13d0 net/mac80211/ibss.c:391
 ieee80211_sta_create_ibss+0x2c7/0x440 net/mac80211/ibss.c:1351
 ieee80211_sta_find_ibss net/mac80211/ibss.c:1481 [inline]
 ieee80211_ibss_work+0xdec/0x1100 net/mac80211/ibss.c:1708
 cfg80211_wiphy_work+0x228/0x260 net/wireless/core.c:444
 process_one_work kernel/workqueue.c:2657 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734
 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815
 kthread+0x2fa/0x390 kernel/kthread.c:388
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1182 [inline]
 free_unref_page_prepare+0x7d7/0x8f0 mm/page_alloc.c:2366
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2459
 __slab_free+0x35a/0x400 mm/slub.c:3759
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:770
 slab_alloc_node mm/slub.c:3518 [inline]
 slab_alloc mm/slub.c:3526 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3533 [inline]
 kmem_cache_alloc_lru+0x175/0x2c0 mm/slub.c:3549
 alloc_inode_sb include/linux/fs.h:2985 [inline]
 sock_alloc_inode+0x28/0xc0 net/socket.c:308
 alloc_inode fs/inode.c:261 [inline]
 new_inode_pseudo+0x63/0x1d0 fs/inode.c:1046
 sock_alloc net/socket.c:634 [inline]
 __sock_create+0x12d/0x940 net/socket.c:1535
 sock_create net/socket.c:1627 [inline]
 __sys_socket_create net/socket.c:1664 [inline]
 __sys_socket+0xd7/0x1b0 net/socket.c:1715
 __do_sys_socket net/socket.c:1729 [inline]
 __se_sys_socket net/socket.c:1727 [inline]
 __x64_sys_socket+0x7a/0x90 net/socket.c:1727
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffff88807c5d1700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88807c5d1780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88807c5d1800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff88807c5d1880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807c5d1900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/11/01 00:28 linux-6.6.y b5a1dc3ad482 2041d3f8 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in gadget_dev_open
2026/10/31 23:53 linux-6.6.y b5a1dc3ad482 2041d3f8 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in gadget_dev_open
2026/10/31 18:33 linux-6.6.y b5a1dc3ad482 2041d3f8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in gadget_dev_open
2026/10/28 09:46 linux-6.6.y 0aebf2870d53 96923c60 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in gadget_dev_open
* Struck through repros no longer work on HEAD.