================================================================== BUG: KASAN: slab-use-after-free in v4l2_fh_init drivers/media/v4l2-core/v4l2-fh.c:25 [inline] BUG: KASAN: slab-use-after-free in v4l2_fh_open+0xca/0x430 drivers/media/v4l2-core/v4l2-fh.c:63 Read of size 8 at addr ffff888058a9c738 by task v4l_id/21271 CPU: 1 PID: 21271 Comm: v4l_id Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:364 [inline] print_report+0xa8/0x210 mm/kasan/report.c:468 kasan_report+0x117/0x150 mm/kasan/report.c:581 v4l2_fh_init drivers/media/v4l2-core/v4l2-fh.c:25 [inline] v4l2_fh_open+0xca/0x430 drivers/media/v4l2-core/v4l2-fh.c:63 em28xx_v4l2_open+0x157/0x980 drivers/media/usb/em28xx/em28xx-video.c:2153 v4l2_open+0x212/0x360 drivers/media/v4l2-core/v4l2-dev.c:427 chrdev_open+0x5cc/0x6a0 fs/char_dev.c:414 do_dentry_open+0x8c6/0x1500 fs/open.c:929 do_open fs/namei.c:3640 [inline] path_openat+0x27f1/0x3230 fs/namei.c:3797 do_filp_open+0x1f5/0x430 fs/namei.c:3824 do_sys_openat2+0x134/0x1d0 fs/open.c:1421 do_sys_open fs/open.c:1436 [inline] __do_sys_openat fs/open.c:1452 [inline] __se_sys_openat fs/open.c:1447 [inline] __x64_sys_openat+0x139/0x160 fs/open.c:1447 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f3e140a7407 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:00007ffc0b4c0590 EFLAGS: 00000202 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f3e14760880 RCX: 00007f3e140a7407 RDX: 0000000000000000 RSI: 00007ffc0b4c0f1b RDI: ffffffffffffff9c RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00007ffc0b4c07e0 R14: 00007f3e148bf000 R15: 000055c60ddf24d8 Allocated by task 18426: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4e/0x70 mm/kasan/common.c:53 ____kasan_kmalloc mm/kasan/common.c:375 [inline] __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:384 kmalloc include/linux/slab.h:600 [inline] kzalloc include/linux/slab.h:721 [inline] em28xx_v4l2_init+0x10b/0x2e70 drivers/media/usb/em28xx/em28xx-video.c:2532 em28xx_init_extension+0x11c/0x1b0 drivers/media/usb/em28xx/em28xx-core.c:1116 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa5d/0x15d0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 Freed by task 18426: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4e/0x70 mm/kasan/common.c:53 kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:237 kasan_slab_free include/linux/kasan.h:164 [inline] slab_free_hook mm/slub.c:1811 [inline] slab_free_freelist_hook+0x130/0x1a0 mm/slub.c:1837 slab_free mm/slub.c:3830 [inline] __kmem_cache_free+0xba/0x1e0 mm/slub.c:3843 em28xx_free_v4l2 drivers/media/usb/em28xx/em28xx-video.c:2118 [inline] kref_put include/linux/kref.h:65 [inline] em28xx_v4l2_init+0x1670/0x2e70 drivers/media/usb/em28xx/em28xx-video.c:2901 em28xx_init_extension+0x11c/0x1b0 drivers/media/usb/em28xx/em28xx-core.c:1116 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa5d/0x15d0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 The buggy address belongs to the object at ffff888058a9c000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 1848 bytes inside of freed 8192-byte region [ffff888058a9c000, ffff888058a9e000) The buggy address belongs to the physical page: page:ffffea000162a600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x58a98 head:ffffea000162a600 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff) page_type: 0xffffffff() raw: 00fff00000000840 ffff888017c42280 ffffea0001aa2800 0000000000000002 raw: 0000000000000000 0000000080020002 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 20558, tgid 20557 (syz.3.4395), ts 1368088199919, free_ts 1367853099192 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1581 prep_new_page mm/page_alloc.c:1588 [inline] get_page_from_freelist+0x1951/0x19e0 mm/page_alloc.c:3220 __alloc_pages+0x1f0/0x460 mm/page_alloc.c:4486 alloc_slab_page+0x5d/0x160 mm/slub.c:1881 allocate_slab mm/slub.c:2028 [inline] new_slab+0x87/0x2d0 mm/slub.c:2081 ___slab_alloc+0xc5d/0x12f0 mm/slub.c:3253 __slab_alloc mm/slub.c:3339 [inline] __slab_alloc_node mm/slub.c:3392 [inline] slab_alloc_node mm/slub.c:3485 [inline] __kmem_cache_alloc_node+0x19e/0x250 mm/slub.c:3534 __do_kmalloc_node mm/slab_common.c:1006 [inline] __kmalloc_node+0xa4/0x230 mm/slab_common.c:1014 kmalloc_node include/linux/slab.h:620 [inline] kvmalloc_node+0x70/0x180 mm/util.c:617 kvmalloc include/linux/slab.h:738 [inline] kvmalloc_array include/linux/slab.h:756 [inline] __ptr_ring_init_queue_alloc include/linux/ptr_ring.h:471 [inline] ptr_ring_init include/linux/ptr_ring.h:489 [inline] skb_array_init include/linux/skb_array.h:182 [inline] pfifo_fast_init+0x238/0x6a0 net/sched/sch_generic.c:870 qdisc_create_dflt+0x11e/0x430 net/sched/sch_generic.c:1019 attach_one_default_qdisc net/sched/sch_generic.c:1176 [inline] netdev_for_each_tx_queue include/linux/netdevice.h:2520 [inline] attach_default_qdiscs net/sched/sch_generic.c:1194 [inline] dev_activate+0x397/0x11a0 net/sched/sch_generic.c:1253 __dev_open+0x347/0x430 net/core/dev.c:1528 __dev_change_flags+0x211/0x6a0 net/core/dev.c:8698 dev_change_flags+0x88/0x1a0 net/core/dev.c:8770 dev_ioctl+0x7b4/0x1140 net/core/dev_ioctl.c:770 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1181 [inline] free_unref_page_prepare+0x7b2/0x8c0 mm/page_alloc.c:2365 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2458 __slab_free+0x35a/0x400 mm/slub.c:3736 qlink_free mm/kasan/quarantine.c:166 [inline] qlist_free_all+0x75/0xd0 mm/kasan/quarantine.c:185 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306 kasan_slab_alloc include/linux/kasan.h:188 [inline] slab_post_alloc_hook+0x6e/0x4b0 mm/slab.h:767 slab_alloc_node mm/slub.c:3495 [inline] slab_alloc mm/slub.c:3503 [inline] __kmem_cache_alloc_lru mm/slub.c:3510 [inline] kmem_cache_alloc+0x11a/0x2d0 mm/slub.c:3519 getname_flags+0xbb/0x500 fs/namei.c:140 user_path_at_empty+0x2c/0x60 fs/namei.c:2916 user_path_at include/linux/namei.h:57 [inline] ksys_umount fs/namespace.c:1921 [inline] __do_sys_umount fs/namespace.c:1929 [inline] __se_sys_umount fs/namespace.c:1927 [inline] __x64_sys_umount+0xfd/0x180 fs/namespace.c:1927 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 Memory state around the buggy address: ffff888058a9c600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888058a9c680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888058a9c700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888058a9c780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888058a9c800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================