================================================================== BUG: KASAN: slab-use-after-free in v4l2_open+0x351/0x490 drivers/media/v4l2-core/v4l2-dev.c:444 Read of size 4 at addr ffff88804aa08860 by task v4l_id/15367 CPU: 1 UID: 0 PID: 15367 Comm: v4l_id Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 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+0x13d/0x4b0 mm/kasan/report.c:482 kasan_report+0xdf/0x1c0 mm/kasan/report.c:595 v4l2_open+0x351/0x490 drivers/media/v4l2-core/v4l2-dev.c:444 chrdev_open+0x234/0x6a0 fs/char_dev.c:411 do_dentry_open+0x6ab/0x14d0 fs/open.c:947 vfs_open+0x82/0x3f0 fs/open.c:1052 do_open fs/namei.c:4700 [inline] path_openat+0x2873/0x4280 fs/namei.c:4863 do_file_open+0x20e/0x430 fs/namei.c:4892 do_sys_openat2+0x10f/0x1e0 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+0x12d/0x210 fs/open.c:1385 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f17fd8a7407 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:00007ffdd8a39110 EFLAGS: 00000202 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f17fdf42880 RCX: 00007f17fd8a7407 RDX: 0000000000000000 RSI: 00007ffdd8a39f1c RDI: ffffffffffffff9c RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00007ffdd8a39360 R14: 00007f17fe0a9000 R15: 000056223f7e14d8 Allocated by task 5691: 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+0x2e5/0x6c0 mm/slub.c:5489 _kmalloc_noprof include/linux/slab.h:988 [inline] _kzalloc_noprof include/linux/slab.h:1309 [inline] em28xx_v4l2_init.cold+0x94/0x3a40 drivers/media/usb/em28xx/em28xx-video.c:2709 em28xx_init_extension+0x13a/0x200 drivers/media/usb/em28xx/em28xx-core.c:1248 request_module_async+0x61/0x80 drivers/media/usb/em28xx/em28xx-cards.c:3660 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322 process_scheduled_works kernel/workqueue.c:3405 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Freed by task 5691: 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:2677 [inline] slab_free mm/slub.c:6377 [inline] kfree+0x22b/0x6c0 mm/slub.c:6692 kref_put.isra.0+0x53/0x75 include/linux/kref.h:65 em28xx_v4l2_init.cold+0x280/0x3a40 drivers/media/usb/em28xx/em28xx-video.c:3080 em28xx_init_extension+0x13a/0x200 drivers/media/usb/em28xx/em28xx-core.c:1248 request_module_async+0x61/0x80 drivers/media/usb/em28xx/em28xx-cards.c:3660 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322 process_scheduled_works kernel/workqueue.c:3405 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 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 ffff88804aa08000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 2144 bytes inside of freed 8192-byte region [ffff88804aa08000, ffff88804aa0a000) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4aa08 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 ffff88813fe22280 dead000000000100 dead000000000122 raw: 0000000000000000 0000000800020002 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88813fe22280 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 14000, tgid 13995 (syz.9.2074), ts 745583719480, free_ts 744563232067 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1859 prep_new_page mm/page_alloc.c:1867 [inline] get_page_from_freelist+0xf48/0x3530 mm/page_alloc.c:3946 __alloc_frozen_pages_noprof+0x299/0x2dc0 mm/page_alloc.c:5304 alloc_slab_page mm/slub.c:3266 [inline] allocate_slab mm/slub.c:3380 [inline] new_slab+0xa2/0x640 mm/slub.c:3426 refill_objects+0xe3/0x410 mm/slub.c:7310 refill_sheaf mm/slub.c:2804 [inline] __pcs_replace_empty_main+0x376/0x680 mm/slub.c:4675 alloc_from_pcs mm/slub.c:4773 [inline] slab_alloc_node mm/slub.c:4905 [inline] __kmalloc_cache_noprof+0x479/0x6c0 mm/slub.c:5485 _kmalloc_noprof include/linux/slab.h:988 [inline] audit_log_d_path+0xed/0x210 kernel/audit.c:2216 audit_log_d_path_exe+0x46/0x80 kernel/audit.c:2432 audit_log_task+0x2fe/0x3a0 kernel/auditsc.c:2904 audit_seccomp+0x7a/0x1f0 kernel/auditsc.c:2951 seccomp_log kernel/seccomp.c:1048 [inline] __seccomp_filter+0x896/0x1140 kernel/seccomp.c:1344 __secure_computing+0x221/0x2e0 kernel/seccomp.c:1404 syscall_trace_enter include/linux/entry-common.h:103 [inline] syscall_enter_from_user_mode_work include/linux/entry-common.h:147 [inline] syscall_enter_from_user_mode include/linux/entry-common.h:178 [inline] do_syscall_64+0x5e2/0x870 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f page last free pid 5582 tgid 5582 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1406 [inline] __free_frozen_pages+0x79f/0x1090 mm/page_alloc.c:2950 __folio_put+0x3b4/0x5f0 mm/swap.c:112 folio_put include/linux/mm.h:2124 [inline] put_page include/linux/mm.h:2193 [inline] put_netmem include/net/netmem.h:394 [inline] skb_page_unref include/linux/skbuff_ref.h:43 [inline] __skb_frag_unref include/linux/skbuff_ref.h:56 [inline] skb_release_data+0x649/0x8e0 net/core/skbuff.c:1116 skb_release_all net/core/skbuff.c:1197 [inline] __kfree_skb+0x4f/0x70 net/core/skbuff.c:1211 tcp_wmem_free_skb include/net/tcp.h:334 [inline] tcp_rtx_queue_unlink_and_free include/net/tcp.h:2321 [inline] tcp_clean_rtx_queue net/ipv4/tcp_input.c:3698 [inline] tcp_ack+0x2079/0x7650 net/ipv4/tcp_input.c:4400 tcp_rcv_established+0x84f/0x3990 net/ipv4/tcp_input.c:6678 tcp_v4_do_rcv+0xbb6/0x1260 net/ipv4/tcp_ipv4.c:1854 sk_backlog_rcv include/net/sock.h:1190 [inline] __release_sock+0x35a/0x440 net/core/sock.c:3260 release_sock+0x1e5/0x280 net/core/sock.c:3859 tcp_sendmsg+0x38/0x50 net/ipv4/tcp.c:1452 inet_sendmsg+0xb9/0x140 net/ipv4/af_inet.c:865 sock_sendmsg_nosec net/socket.c:775 [inline] __sock_sendmsg net/socket.c:790 [inline] sock_write_iter+0x4ea/0x5b0 net/socket.c:1241 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1050 fs/read_write.c:687 ksys_write+0x1f8/0x250 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff88804aa08700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88804aa08780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88804aa08800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88804aa08880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88804aa08900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================