================================================================== 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 ffff8880833ac748 by task v4l_id/27526 CPU: 1 UID: 0 PID: 27526 Comm: v4l_id Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 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:4671 [inline] path_openat+0x208c/0x31a0 fs/namei.c:4830 do_file_open+0x20e/0x430 fs/namei.c:4859 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: 0033:0x7f00d82a7407 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:00007fffd4ba5710 EFLAGS: 00000202 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f00d8a10880 RCX: 00007f00d82a7407 RDX: 0000000000000000 RSI: 00007fffd4ba6f1a RDI: ffffffffffffff9c RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00007fffd4ba5960 R14: 00007f00d8b77000 R15: 000055c7469d64d8 Allocated by task 25067: 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:962 [inline] kzalloc_noprof include/linux/slab.h:1200 [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+0x9d7/0x1920 kernel/workqueue.c:3275 process_scheduled_works kernel/workqueue.c:3358 [inline] worker_thread+0x5da/0xe40 kernel/workqueue.c:3439 kthread+0x370/0x450 kernel/kthread.c:467 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 25067: 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:2687 [inline] slab_free mm/slub.c:6124 [inline] kfree+0x1f6/0x6b0 mm/slub.c:6442 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+0x9d7/0x1920 kernel/workqueue.c:3275 process_scheduled_works kernel/workqueue.c:3358 [inline] worker_thread+0x5da/0xe40 kernel/workqueue.c:3439 kthread+0x370/0x450 kernel/kthread.c:467 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 ffff8880833ac000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 1864 bytes inside of freed 8192-byte region [ffff8880833ac000, ffff8880833ae000) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x833a8 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 ffff88813fe3b280 dead000000000100 dead000000000122 raw: 0000000000000000 0000000000020002 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88813fe3b280 dead000000000100 dead000000000122 head: 0000000000000000 0000000000020002 00000000f5000000 0000000000000000 head: 00fff00000000003 ffffea00020cea01 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 0x152820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL), pid 20554, tgid 20554 (syz-executor), ts 1667367566931, free_ts 1665780942048 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_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2484 alloc_slab_page mm/slub.c:3253 [inline] allocate_slab mm/slub.c:3444 [inline] new_slab+0x43a/0x6d0 mm/slub.c:3502 ___slab_alloc+0x2a0/0x850 mm/slub.c:4376 __slab_alloc_node mm/slub.c:4442 [inline] slab_alloc_node mm/slub.c:4818 [inline] __kmalloc_cache_noprof+0x374/0x6f0 mm/slub.c:5334 kmalloc_noprof include/linux/slab.h:962 [inline] audit_log_d_path+0xed/0x210 kernel/audit.c:2196 audit_log_lsm_data+0x5bc/0x1fa0 security/lsm_audit.c:225 dump_common_audit_data security/lsm_audit.c:421 [inline] common_lsm_audit+0x229/0x2b0 security/lsm_audit.c:451 slow_avc_audit+0x186/0x210 security/selinux/avc.c:779 avc_xperms_audit security/selinux/avc.c:425 [inline] avc_has_extended_perms+0x9b7/0x1080 security/selinux/avc.c:1090 ioctl_has_perm.constprop.0.isra.0+0x376/0x540 security/selinux/hooks.c:3863 selinux_file_ioctl+0x139/0x290 security/selinux/hooks.c:3911 security_file_ioctl+0xfb/0x230 security/security.c:2435 __do_sys_ioctl fs/ioctl.c:591 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0xb7/0x210 fs/ioctl.c:583 page last free pid 5790 tgid 5790 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] put_netmem include/net/netmem.h:420 [inline] skb_page_unref include/linux/skbuff_ref.h:43 [inline] __skb_frag_unref include/linux/skbuff_ref.h:56 [inline] skb_release_data+0x667/0x9d0 net/core/skbuff.c:1122 skb_release_all net/core/skbuff.c:1203 [inline] __kfree_skb net/core/skbuff.c:1217 [inline] napi_consume_skb+0x2be/0x320 net/core/skbuff.c:1546 skb_defer_free_flush+0x1f1/0x290 net/core/dev.c:6812 net_rx_action+0x3ca/0xf20 net/core/dev.c:7880 handle_softirqs+0x1eb/0x9e0 kernel/softirq.c:622 do_softirq kernel/softirq.c:523 [inline] do_softirq+0xac/0xe0 kernel/softirq.c:510 __local_bh_enable_ip+0xf8/0x120 kernel/softirq.c:450 local_bh_enable include/linux/bottom_half.h:33 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:924 [inline] __dev_queue_xmit+0x7f1/0x4750 net/core/dev.c:4863 dev_queue_xmit include/linux/netdevice.h:3384 [inline] neigh_hh_output include/net/neighbour.h:540 [inline] neigh_output include/net/neighbour.h:554 [inline] ip_finish_output2+0xf4a/0x24d0 net/ipv4/ip_output.c:237 __ip_finish_output.part.0+0x444/0x6f0 net/ipv4/ip_output.c:315 __ip_finish_output net/ipv4/ip_output.c:303 [inline] ip_finish_output net/ipv4/ip_output.c:325 [inline] NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip_output+0x39b/0xec0 net/ipv4/ip_output.c:438 dst_output include/net/dst.h:470 [inline] ip_local_out net/ipv4/ip_output.c:131 [inline] __ip_queue_xmit+0x1b73/0x22b0 net/ipv4/ip_output.c:534 __tcp_transmit_skb+0x3347/0x4b50 net/ipv4/tcp_output.c:1693 tcp_transmit_skb net/ipv4/tcp_output.c:1711 [inline] tcp_write_xmit+0x12a2/0x8980 net/ipv4/tcp_output.c:3064 Memory state around the buggy address: ffff8880833ac600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880833ac680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880833ac700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880833ac780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880833ac800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb 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