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

Status: upstream: reported syz repro on 2026/08/27 18:53
Subsystems: media usb
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+537b5eb78cebbff5ea70@syzkaller.appspotmail.com
First crash: 3d13h, last: 3d13h
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
d46c8740 patching 💥 KASAN: slab-use-after-free Read in sd_stopN 2026/08/28 19:14 2026/08/28 19:14 2026/08/28 19:49 bcbc8ceb
35d576b4 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ✅ VMHostTrigger: ❌ ❓ KASAN: slab-use-after-free Read in sd_stopN 2026/08/26 03:17 2026/08/26 03:17 2026/08/26 03:22 ee98d2fd
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Title Replies (including bot) Last reply
[syzbot] [media?] [usb?] KASAN: slab-use-after-free Read in sd_stopN 0 (1) 2026/08/27 18:53
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 KASAN: use-after-free Read in sd_stopN 19 1 24d 24d 0/3 upstream: reported on 2026/08/05 01:57

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in sd_stopN+0xaf/0xc0 drivers/media/usb/gspca/ov534_9.c:1615
Read of size 4 at addr ffff8880582fc000 by task syz.2.154/6638

CPU: 1 UID: 0 PID: 6638 Comm: syz.2.154 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x13d/0x4b0 mm/kasan/report.c:482
 kasan_report+0xdf/0x1c0 mm/kasan/report.c:595
 sd_stopN+0xaf/0xc0 drivers/media/usb/gspca/ov534_9.c:1615
 gspca_stream_off+0xd5/0x470 drivers/media/usb/gspca/gspca.c:737
 gspca_stop_streaming+0x34/0x50 drivers/media/usb/gspca/gspca.c:1365
 __vb2_queue_cancel+0xb8/0xe90 drivers/media/common/videobuf2/videobuf2-core.c:2199
 vb2_core_streamoff+0x5e/0x140 drivers/media/common/videobuf2/videobuf2-core.c:2376
 __vb2_cleanup_fileio.isra.0+0x6e/0x160 drivers/media/common/videobuf2/videobuf2-core.c:2974
 vb2_core_queue_release+0x1f/0x190 drivers/media/common/videobuf2/videobuf2-core.c:2676
 vb2_queue_release drivers/media/common/videobuf2/videobuf2-v4l2.c:943 [inline]
 _vb2_fop_release+0xe8/0x280 drivers/media/common/videobuf2/videobuf2-v4l2.c:1146
 v4l2_release+0x280/0x390 drivers/media/v4l2-core/v4l2-dev.c:471
 __fput+0x3ff/0xb50 fs/file_table.c:512
 task_work_run+0x150/0x240 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x951/0x2ae0 kernel/exit.c:1008
 do_group_exit+0xd5/0x2a0 kernel/exit.c:1151
 get_signal+0x1ec7/0x21e0 kernel/signal.c:3046
 arch_do_signal_or_restart+0x91/0x7e0 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop+0x139/0x700 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:336 [inline]
 do_syscall_64+0x661/0x790 arch/x86/entry/syscall_64.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0daab9e0d9
Code: Unable to access opcode bytes at 0x7f0daab9e0af.
RSP: 002b:00007f0daba48028 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: fffffffffffffe00 RBX: 00007f0daae26090 RCX: 00007f0daab9e0d9
RDX: 0000000000001000 RSI: 0000200000000600 RDI: 0000000000000005
RBP: 00007f0daac35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0daae26128 R14: 00007f0daae26090 R15: 00007ffd25d699f8
 </TASK>

Allocated by task 2317:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x2e7/0x6b0 mm/slub.c:5484
 _kmalloc_noprof include/linux/slab.h:988 [inline]
 _kzalloc_noprof include/linux/slab.h:1309 [inline]
 usb_alloc_dev+0x55/0x1090 drivers/usb/core/usb.c:651
 hub_port_connect drivers/usb/core/hub.c:5478 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5715 [inline]
 port_event drivers/usb/core/hub.c:5879 [inline]
 hub_event+0x2b93/0x4420 drivers/usb/core/hub.c:5961
 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387
 process_scheduled_works kernel/workqueue.c:3470 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 2317:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2678 [inline]
 slab_free mm/slub.c:6372 [inline]
 kfree+0x22b/0x6c0 mm/slub.c:6687
 device_release+0xd2/0x270 drivers/base/core.c:2640
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1f7/0x640 lib/kobject.c:737
 put_device+0x1f/0x30 drivers/base/core.c:3884
 hub_port_connect drivers/usb/core/hub.c:5415 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5715 [inline]
 port_event drivers/usb/core/hub.c:5879 [inline]
 hub_event+0x1bb1/0x4420 drivers/usb/core/hub.c:5961
 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387
 process_scheduled_works kernel/workqueue.c:3470 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x730/0xd60 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 ffff8880582fc000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 0 bytes inside of
 freed 2048-byte region [ffff8880582fc000, ffff8880582fc800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8880582fa000 pfn:0x582f8
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000240 ffff88801c042f00 ffffea0000d28010 ffffea0001636a10
raw: ffff8880582fa000 0000000800080006 00000000f5000000 0000000000000000
head: 00fff00000000240 ffff88801c042f00 ffffea0000d28010 ffffea0001636a10
head: ffff8880582fa000 0000000800080006 00000000f5000000 0000000000000000
head: 00fff00000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 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 5872, tgid 5872 (syz-executor), ts 140556794415
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1871
 prep_new_page mm/page_alloc.c:1879 [inline]
 get_page_from_freelist+0x110d/0x35b0 mm/page_alloc.c:3943
 __alloc_frozen_pages_noprof+0x2eb/0x3300 mm/page_alloc.c:5436
 alloc_slab_page mm/slub.c:3267 [inline]
 allocate_slab mm/slub.c:3382 [inline]
 new_slab+0xa5/0x640 mm/slub.c:3428
 refill_objects+0xe3/0x410 mm/slub.c:7305
 refill_sheaf mm/slub.c:2805 [inline]
 __pcs_replace_empty_main+0x372/0x680 mm/slub.c:4677
 alloc_from_pcs mm/slub.c:4775 [inline]
 slab_alloc_node mm/slub.c:4907 [inline]
 __kmalloc_cache_noprof+0x47b/0x6b0 mm/slub.c:5480
 _kmalloc_noprof include/linux/slab.h:988 [inline]
 rtnl_newlink+0x139/0x2620 net/core/rtnetlink.c:4113
 rtnetlink_rcv_msg+0x95e/0xe90 net/core/rtnetlink.c:7132
 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2556
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec net/socket.c:800 [inline]
 __sock_sendmsg net/socket.c:815 [inline]
 __sys_sendto+0x48b/0x4e0 net/socket.c:2281
 __do_sys_sendto net/socket.c:2288 [inline]
 __se_sys_sendto net/socket.c:2284 [inline]
 __x64_sys_sendto+0xe0/0x1c0 net/socket.c:2284
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5872 tgid 5872 ts 140543763839 stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 __free_pages_prepare mm/page_alloc.c:1418 [inline]
 __free_frozen_pages+0x79f/0x10f0 mm/page_alloc.c:2962
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4586 [inline]
 slab_alloc_node mm/slub.c:4919 [inline]
 __do_kmalloc_node mm/slub.c:5336 [inline]
 __kvmalloc_node_noprof+0x2ed/0x970 mm/slub.c:6900
 netif_alloc_netdev_queues net/core/dev.c:11291 [inline]
 alloc_netdev_mqs+0xb4e/0x15c0 net/core/dev.c:12187
 rtnl_create_link+0xc13/0xf80 net/core/rtnetlink.c:3777
 rtnl_newlink_create net/core/rtnetlink.c:3959 [inline]
 __rtnl_newlink net/core/rtnetlink.c:4098 [inline]
 rtnl_newlink+0x15bc/0x2620 net/core/rtnetlink.c:4215
 rtnetlink_rcv_msg+0x95e/0xe90 net/core/rtnetlink.c:7132
 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2556
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec net/socket.c:800 [inline]
 __sock_sendmsg net/socket.c:815 [inline]
 __sys_sendto+0x48b/0x4e0 net/socket.c:2281
 __do_sys_sendto net/socket.c:2288 [inline]
 __se_sys_sendto net/socket.c:2284 [inline]
 __x64_sys_sendto+0xe0/0x1c0 net/socket.c:2284
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff8880582fbf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880582fbf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880582fc000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8880582fc080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880582fc100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/26 03:17 upstream 818bebeb63dd 6a91adb4 .config console log report syz / log [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Read in sd_stopN
* Struck through repros no longer work on HEAD.