================================================================== BUG: KASAN: slab-use-after-free in v4l2_fh_init+0x27d/0x2c0 drivers/media/v4l2-core/v4l2-fh.c:25 Read of size 8 at addr ffff88806ba68790 by task v4l_id/26453 CPU: 1 UID: 0 PID: 26453 Comm: v4l_id Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Call Trace: __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+0x156/0x4c9 mm/kasan/report.c:482 kasan_report+0xdf/0x1e0 mm/kasan/report.c:595 v4l2_fh_init+0x27d/0x2c0 drivers/media/v4l2-core/v4l2-fh.c:25 v4l2_fh_open+0x64/0xa0 drivers/media/v4l2-core/v4l2-fh.c:64 em28xx_v4l2_open+0x11e/0x570 drivers/media/usb/em28xx/em28xx-video.c:2153 v4l2_open+0x1d2/0x490 drivers/media/v4l2-core/v4l2-dev.c:433 chrdev_open+0x234/0x6a0 fs/char_dev.c:411 do_dentry_open+0x6d8/0x1660 fs/open.c:949 vfs_open+0x82/0x3f0 fs/open.c:1081 do_open fs/namei.c:4677 [inline] path_openat+0x208c/0x31a0 fs/namei.c:4836 do_file_open+0x20e/0x430 fs/namei.c:4865 do_sys_openat2+0x10d/0x1e0 fs/open.c:1366 do_sys_open fs/open.c:1372 [inline] __do_sys_openat fs/open.c:1388 [inline] __se_sys_openat fs/open.c:1383 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1383 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb2e1ea7407 Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff RSP: 002b:00007ffc507576d0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fb2e255c880 RCX: 00007fb2e1ea7407 RDX: 0000000000000000 RSI: 00007ffc50757f1a RDI: ffffffffffffff9c RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00007ffc50757920 R14: 00007fb2e26c3000 R15: 0000560655a934d8 Allocated by task 16088: 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 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] em28xx_v4l2_init.cold+0x94/0x3503 drivers/media/usb/em28xx/em28xx-video.c:2532 em28xx_init_extension+0x13a/0x200 drivers/media/usb/em28xx/em28xx-core.c:1117 request_module_async+0x61/0x80 drivers/media/usb/em28xx/em28xx-cards.c:3457 process_one_work+0xa23/0x19a0 kernel/workqueue.c:3276 process_scheduled_works kernel/workqueue.c:3359 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3440 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Freed by task 16088: 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:2685 [inline] slab_free mm/slub.c:6165 [inline] kfree+0x1f6/0x6b0 mm/slub.c:6483 kref_put.isra.0+0x56/0x90 include/linux/kref.h:65 em28xx_v4l2_init.cold+0x280/0x3503 drivers/media/usb/em28xx/em28xx-video.c:2901 em28xx_init_extension+0x13a/0x200 drivers/media/usb/em28xx/em28xx-core.c:1117 request_module_async+0x61/0x80 drivers/media/usb/em28xx/em28xx-cards.c:3457 process_one_work+0xa23/0x19a0 kernel/workqueue.c:3276 process_scheduled_works kernel/workqueue.c:3359 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3440 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x754/0xd80 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 ffff88806ba68000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 1936 bytes inside of freed 8192-byte region [ffff88806ba68000, ffff88806ba6a000) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x6ba68 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88813fe41280 dead000000000122 0000000000000000 raw: 0000000000000000 0000000800020002 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88813fe41280 dead000000000122 0000000000000000 head: 0000000000000000 0000000800020002 00000000f5000000 0000000000000000 head: 00fff00000000003 ffffea0001ae9a01 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 0xd28c0(GFP_NOWAIT|__GFP_IO|__GFP_FS|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 26414, tgid 26414 (syz-executor), ts 1510136975693, free_ts 1498069627970 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x153/0x170 mm/page_alloc.c:1889 prep_new_page mm/page_alloc.c:1897 [inline] get_page_from_freelist+0x111d/0x3140 mm/page_alloc.c:3962 __alloc_frozen_pages_noprof+0x27c/0x2ba0 mm/page_alloc.c:5250 alloc_slab_page mm/slub.c:3292 [inline] allocate_slab mm/slub.c:3481 [inline] new_slab+0xa6/0x6b0 mm/slub.c:3539 refill_objects+0x26b/0x400 mm/slub.c:7175 refill_sheaf mm/slub.c:2812 [inline] __pcs_replace_empty_main+0x1ab/0x660 mm/slub.c:4615 alloc_from_pcs mm/slub.c:4717 [inline] slab_alloc_node mm/slub.c:4851 [inline] __do_kmalloc_node mm/slub.c:5259 [inline] __kvmalloc_node_noprof+0x7da/0xa00 mm/slub.c:6752 kvmalloc_array_node_noprof include/linux/slab.h:1216 [inline] __ptr_ring_init_queue_alloc_noprof include/linux/ptr_ring.h:481 [inline] ptr_ring_init_noprof include/linux/ptr_ring.h:499 [inline] wg_packet_queue_init+0x9a/0x360 drivers/net/wireguard/queueing.c:32 wg_newlink+0x2fa/0x7a0 drivers/net/wireguard/device.c:352 rtnl_newlink_create net/core/rtnetlink.c:3862 [inline] __rtnl_newlink net/core/rtnetlink.c:3993 [inline] rtnl_newlink+0x1499/0x2380 net/core/rtnetlink.c:4108 rtnetlink_rcv_msg+0x95e/0xe90 net/core/rtnetlink.c:6994 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2550 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] __sys_sendto+0x468/0x4b0 net/socket.c:2206 __do_sys_sendto net/socket.c:2213 [inline] __se_sys_sendto net/socket.c:2209 [inline] __x64_sys_sendto+0xe0/0x1c0 net/socket.c:2209 page last free pid 26241 tgid 26234 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1433 [inline] __free_frozen_pages+0x7e1/0x10d0 mm/page_alloc.c:2978 __folio_put+0x3b4/0x540 mm/swap.c:112 folio_put include/linux/mm.h:1817 [inline] put_page include/linux/mm.h:1886 [inline] sk_msg_free_elem+0x27b/0x620 net/core/skmsg.c:187 __sk_msg_free+0x11e/0x380 net/core/skmsg.c:201 tls_sw_release_resources_tx+0x391/0x680 net/tls/tls_sw.c:2574 tls_sk_proto_cleanup net/tls/tls_main.c:349 [inline] tls_sk_proto_close+0x661/0xab0 net/tls/tls_main.c:379 inet_release+0xed/0x200 net/ipv4/af_inet.c:443 inet6_release+0x4f/0x70 net/ipv6/af_inet6.c:479 __sock_release+0xb3/0x260 net/socket.c:662 sock_close+0x1c/0x30 net/socket.c:1455 __fput+0x3ff/0xb40 fs/file_table.c:469 task_work_run+0x150/0x240 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:67 [inline] exit_to_user_mode_loop+0x100/0x4a0 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline] do_syscall_64+0x67c/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff88806ba68680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88806ba68700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88806ba68780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88806ba68800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88806ba68880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================