================================================================== BUG: KASAN: slab-use-after-free in v4l2_open+0x395/0x3a0 drivers/media/v4l2-core/v4l2-dev.c:444 Read of size 4 at addr ffff888052fe8860 by task v4l_id/9113 CPU: 1 UID: 0 PID: 9113 Comm: v4l_id Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description+0x55/0x1e0 mm/kasan/report.c:378 print_report+0x58/0x70 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 v4l2_open+0x395/0x3a0 drivers/media/v4l2-core/v4l2-dev.c:444 chrdev_open+0x4cd/0x5e0 fs/char_dev.c:411 do_dentry_open+0x822/0x13a0 fs/open.c:947 vfs_open+0x3b/0x340 fs/open.c:1079 do_open fs/namei.c:4699 [inline] path_openat+0x2e08/0x3860 fs/namei.c:4858 do_file_open+0x23e/0x4a0 fs/namei.c:4887 do_sys_openat2+0x113/0x200 fs/open.c:1364 do_sys_open fs/open.c:1370 [inline] __do_sys_openat fs/open.c:1386 [inline] __se_sys_openat fs/open.c:1381 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1381 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fdd66ca7407 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:00007ffd7709c250 EFLAGS: 00000202 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fdd6738a880 RCX: 00007fdd66ca7407 RDX: 0000000000000000 RSI: 00007ffd7709df1c RDI: ffffffffffffff9c RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00007ffd7709c4a0 R14: 00007fdd6748f000 R15: 000055954641a4d8 Allocated by task 5764: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5420 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] em28xx_v4l2_init+0x10b/0x2eb0 drivers/media/usb/em28xx/em28xx-video.c:2707 em28xx_init_extension+0x120/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1248 process_one_work kernel/workqueue.c:3314 [inline] process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478 kthread+0x389/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Freed by task 5764: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2689 [inline] slab_free mm/slub.c:6251 [inline] kfree+0x1c5/0x640 mm/slub.c:6566 em28xx_free_v4l2 drivers/media/usb/em28xx/em28xx-video.c:2287 [inline] kref_put include/linux/kref.h:65 [inline] em28xx_v4l2_init+0x1685/0x2eb0 drivers/media/usb/em28xx/em28xx-video.c:3078 em28xx_init_extension+0x120/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1248 process_one_work kernel/workqueue.c:3314 [inline] process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478 kthread+0x389/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 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 ffff888052fe8000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 2144 bytes inside of freed 8192-byte region [ffff888052fe8000, ffff888052fea000) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x52fe8 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 ffff88813fe1c280 dead000000000100 dead000000000122 raw: 0000000000000000 0000000800020002 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88813fe1c280 dead000000000100 dead000000000122 head: 0000000000000000 0000000800020002 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 0xd28c0(GFP_NOWAIT|__GFP_IO|__GFP_FS|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 8778, tgid 8778 (syz-executor), ts 647820715050, free_ts 647807795422 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853 prep_new_page mm/page_alloc.c:1861 [inline] get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221 alloc_slab_page mm/slub.c:3278 [inline] allocate_slab+0x77/0x660 mm/slub.c:3467 new_slab mm/slub.c:3525 [inline] refill_objects+0x339/0x3d0 mm/slub.c:7272 refill_sheaf mm/slub.c:2816 [inline] __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652 alloc_from_pcs mm/slub.c:4750 [inline] slab_alloc_node mm/slub.c:4884 [inline] __do_kmalloc_node mm/slub.c:5295 [inline] __kvmalloc_node_noprof+0x657/0x8a0 mm/slub.c:6833 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] skb_array_init_noprof include/linux/skb_array.h:182 [inline] pfifo_fast_init+0x242/0x6c0 net/sched/sch_generic.c:895 qdisc_create_dflt+0x13b/0x4e0 net/sched/sch_generic.c:1038 attach_one_default_qdisc net/sched/sch_generic.c:1197 [inline] netdev_for_each_tx_queue include/linux/netdevice.h:2706 [inline] attach_default_qdiscs net/sched/sch_generic.c:1215 [inline] dev_activate+0x378/0x1150 net/sched/sch_generic.c:1274 __dev_open+0x67a/0x830 net/core/dev.c:1711 __dev_change_flags+0x2fa/0x7e0 net/core/dev.c:9758 netif_change_flags+0x88/0x1a0 net/core/dev.c:9821 do_setlink+0xfa5/0x45a0 net/core/rtnetlink.c:3181 rtnl_changelink net/core/rtnetlink.c:3800 [inline] __rtnl_newlink net/core/rtnetlink.c:3973 [inline] rtnl_newlink+0x15ad/0x1bb0 net/core/rtnetlink.c:4110 rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6997 page last free pid 8778 tgid 8778 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1397 [inline] __free_frozen_pages+0xc1c/0xd30 mm/page_alloc.c:2938 __slab_free+0x274/0x2c0 mm/slub.c:5613 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4570 [inline] slab_alloc_node mm/slub.c:4899 [inline] __kmalloc_cache_noprof+0x2ba/0x660 mm/slub.c:5415 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] kset_create lib/kobject.c:965 [inline] kset_create_and_add+0x5a/0x170 lib/kobject.c:1008 register_queue_kobjects net/core/net-sysfs.c:2091 [inline] netdev_register_kobject+0x1a2/0x310 net/core/net-sysfs.c:2347 register_netdevice+0x1456/0x1ec0 net/core/dev.c:11423 tun_set_iff+0x844/0xf00 drivers/net/tun.c:2812 __tun_chr_ioctl+0x7bb/0x1e10 drivers/net/tun.c:3093 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff888052fe8700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888052fe8780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888052fe8800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888052fe8880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888052fe8900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================