================================================================== 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 ffff888123e88858 by task v4l_id/25189 CPU: 1 UID: 0 PID: 25189 Comm: v4l_id Not tainted syzkaller #0 PREEMPT(lazy) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 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+0x68b/0x14b0 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+0x10b/0x7f0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f008425c407 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:00007fff8cc1b880 EFLAGS: 00000202 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f008416e880 RCX: 00007f008425c407 RDX: 0000000000000000 RSI: 00007fff8cc1bf22 RDI: ffffffffffffff9c RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00007fff8cc1bad0 R14: 00007f00849f2000 R15: 0000556d829db4d8 Allocated by task 5488: 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+0x8f/0xa0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_noprof+0x35e/0x670 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+0x69a/0xc80 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Freed by task 5488: 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+0x43/0x70 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+0x20c/0x650 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+0x69a/0xc80 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 ffff888123e88000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 2136 bytes inside of freed 8192-byte region [ffff888123e88000, ffff888123e8a000) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x123e88 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0x200000000000040(head|node=0|zone=2) page_type: f5(slab) raw: 0200000000000040 ffff888100042280 dead000000000100 dead000000000122 raw: 0000000000000000 0000000800020002 00000000f5000000 0000000000000000 head: 0200000000000040 ffff888100042280 dead000000000100 dead000000000122 head: 0000000000000000 0000000800020002 00000000f5000000 0000000000000000 head: 0200000000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff head: 0000000000000000 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 2976, tgid 2976 (syz-executor), ts 41109741803, free_ts 39283949975 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+0xf25/0x3400 mm/page_alloc.c:3946 __alloc_frozen_pages_noprof+0x28f/0x2b90 mm/page_alloc.c:5304 alloc_slab_page mm/slub.c:3266 [inline] allocate_slab mm/slub.c:3380 [inline] new_slab+0xa2/0x670 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+0x50e/0x670 mm/slub.c:5485 _kmalloc_noprof include/linux/slab.h:988 [inline] _kzalloc_noprof include/linux/slab.h:1309 [inline] mr_table_alloc+0x61/0x3e0 net/ipv4/ipmr_base.c:55 ipmr_new_table net/ipv4/ipmr.c:438 [inline] ipmr_rules_init net/ipv4/ipmr.c:339 [inline] ipmr_net_init+0x295/0x3f0 net/ipv4/ipmr.c:3310 ops_init+0x1e2/0x5f0 net/core/net_namespace.c:137 setup_net+0x118/0x3a0 net/core/net_namespace.c:446 copy_net_ns+0x46f/0x7c0 net/core/net_namespace.c:579 create_new_namespaces+0x3ea/0xac0 kernel/nsproxy.c:132 unshare_nsproxy_namespaces+0xf2/0x220 kernel/nsproxy.c:234 ksys_unshare+0x438/0xab0 kernel/fork.c:3269 __do_sys_unshare kernel/fork.c:3343 [inline] __se_sys_unshare kernel/fork.c:3341 [inline] __x64_sys_unshare+0x31/0x40 kernel/fork.c:3341 page last free pid 2959 tgid 2959 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1406 [inline] __free_frozen_pages+0x716/0xf50 mm/page_alloc.c:2950 __folio_put+0x278/0x470 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:1110 skb_release_all net/core/skbuff.c:1191 [inline] __kfree_skb+0x4f/0x70 net/core/skbuff.c:1205 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+0x1f96/0x7420 net/ipv4/tcp_input.c:4400 tcp_rcv_established+0x116d/0x3990 net/ipv4/tcp_input.c:6589 tcp_v4_do_rcv+0x5bb/0xc30 net/ipv4/tcp_ipv4.c:1854 sk_backlog_rcv include/net/sock.h:1190 [inline] __release_sock+0x35a/0x440 net/core/sock.c:3261 __sk_flush_backlog+0x27/0xc0 net/core/sock.c:3284 sk_flush_backlog include/net/sock.h:1253 [inline] tcp_sendmsg_locked+0x3a44/0x4430 net/ipv4/tcp.c:1252 tcp_sendmsg+0x2e/0x50 net/ipv4/tcp.c:1451 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+0x10b/0x7f0 arch/x86/entry/syscall_64.c:94 Memory state around the buggy address: ffff888123e88700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888123e88780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888123e88800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888123e88880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888123e88900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================