=========================================================[ 1576.195278][T27636] ================================================================== BUG: KASAN: slab-out-of-bounds in v4l2_open+0x398/0x3a0 drivers/media/v4l2-core/v4l2-dev.c:444 Read of size 4 at addr ffff88808d2d49d0 by task v4l_id/27636 CPU: 0 UID: 0 PID: 27636 Comm: v4l_id Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 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+0x398/0x3a0 drivers/media/v4l2-core/v4l2-dev.c:444 chrdev_open+0x4d0/0x5f0 fs/char_dev.c:411 do_dentry_open+0x83d/0x13e0 fs/open.c:947 vfs_open+0x3b/0x350 fs/open.c:1052 do_open fs/namei.c:4688 [inline] path_openat+0x2eea/0x3960 fs/namei.c:4847 do_file_open+0x23e/0x4a0 fs/namei.c:4876 do_sys_openat2+0x115/0x200 fs/open.c:1368 do_sys_open fs/open.c:1374 [inline] __do_sys_openat fs/open.c:1390 [inline] __se_sys_openat fs/open.c:1385 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1385 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fca1e60c407 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:00007ffe1c5c5260 EFLAGS: 00000202 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fca1e51e880 RCX: 00007fca1e60c407 RDX: 0000000000000000 RSI: 00007ffe1c5c6f1a RDI: ffffffffffffff9c RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00007ffe1c5c54b0 R14: 00007fca1eda2000 R15: 00005648c82e24d8 The buggy address belongs to the object at ffff88808d2d49c0 which belongs to the cache skbuff_small_head of size 704 The buggy address is located 16 bytes inside of allocated 704-byte region [ffff88808d2d49c0, ffff88808d2d4c80) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x8d2d4 head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x80000000000040(head|node=0|zone=1) page_type: f5(slab) raw: 0080000000000040 ffff88801f2dddc0 dead000000000122 0000000000000000 raw: 0000000000000000 0000000800130013 00000000f5000000 0000000000000000 head: 0080000000000040 ffff88801f2dddc0 dead000000000122 0000000000000000 head: 0000000000000000 0000000800130013 00000000f5000000 0000000000000000 head: 0080000000000002 ffffffffffffff01 00000000ffffffff 00000000ffffffff head: ffff88808d2d5000 0000000000000000 00000000ffffffff 0000000000000004 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0xf2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_MEMALLOC|__GFP_COMP|__GFP_NOMEMALLOC), pid 1199, tgid 1199 (irq/31-virtio1-), ts 1576160272757, free_ts 1576144264759 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1866 prep_new_page mm/page_alloc.c:1874 [inline] get_page_from_freelist+0x265c/0x26e0 mm/page_alloc.c:3953 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5296 alloc_slab_page mm/slub.c:3289 [inline] allocate_slab+0x74/0x5e0 mm/slub.c:3404 new_slab mm/slub.c:3447 [inline] refill_objects+0x33c/0x3d0 mm/slub.c:7226 refill_sheaf mm/slub.c:2827 [inline] __pcs_replace_empty_main+0x373/0x720 mm/slub.c:4665 alloc_from_pcs mm/slub.c:4763 [inline] slab_alloc_node mm/slub.c:4897 [inline] kmem_cache_alloc_node_noprof+0x4f4/0x6e0 mm/slub.c:4964 kmalloc_reserve net/core/skbuff.c:613 [inline] __alloc_skb+0x27d/0x7d0 net/core/skbuff.c:713 napi_alloc_skb+0x9d/0x780 net/core/skbuff.c:853 page_to_skb+0x232/0x1620 drivers/net/virtio_net.c:884 receive_mergeable drivers/net/virtio_net.c:2411 [inline] receive_buf+0x770/0x1c20 drivers/net/virtio_net.c:2575 virtnet_receive_packets drivers/net/virtio_net.c:2900 [inline] virtnet_receive drivers/net/virtio_net.c:2924 [inline] virtnet_poll+0x2201/0x3060 drivers/net/virtio_net.c:3013 __napi_poll+0xab/0x550 net/core/dev.c:7735 napi_poll net/core/dev.c:7798 [inline] net_rx_action+0x696/0xe00 net/core/dev.c:7955 handle_softirqs+0x1de/0x6d0 kernel/softirq.c:626 __do_softirq kernel/softirq.c:660 [inline] __local_bh_enable_ip+0x170/0x2b0 kernel/softirq.c:302 page last free pid 25377 tgid 25377 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1413 [inline] __free_frozen_pages+0x10af/0x1190 mm/page_alloc.c:2957 em28xx_free_v4l2 drivers/media/usb/em28xx/em28xx-video.c:2289 [inline] kref_put include/linux/kref.h:65 [inline] em28xx_v4l2_init+0x18e9/0x3320 drivers/media/usb/em28xx/em28xx-video.c:3080 em28xx_init_extension+0x120/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1248 process_one_work+0x98b/0x1630 kernel/workqueue.c:3318 process_scheduled_works kernel/workqueue.c:3401 [inline] worker_thread+0xb49/0x1140 kernel/workqueue.c:3482 kthread+0x388/0x470 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 Memory state around the buggy address: ffff88808d2d4880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88808d2d4900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88808d2d4980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff88808d2d4a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88808d2d4a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================