================================================================== BUG: KASAN: use-after-free in v4l2_open+0x32d/0x340 drivers/media/v4l2-core/v4l2-dev.c:432 Read of size 4 at addr ffff88807d9e47e8 by task v4l_id/20914 CPU: 0 PID: 20914 Comm: v4l_id Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Call Trace: dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106 print_address_description mm/kasan/report.c:316 [inline] print_report+0xa8/0x210 mm/kasan/report.c:420 kasan_report+0x10b/0x140 mm/kasan/report.c:524 v4l2_open+0x32d/0x340 drivers/media/v4l2-core/v4l2-dev.c:432 chrdev_open+0x585/0x5f0 fs/char_dev.c:414 do_dentry_open+0x7dd/0x10b0 fs/open.c:882 do_open fs/namei.c:3634 [inline] path_openat+0x2674/0x2f10 fs/namei.c:3791 do_filp_open+0x1ee/0x420 fs/namei.c:3818 do_sys_openat2+0x14b/0x4f0 fs/open.c:1320 do_sys_open fs/open.c:1336 [inline] __do_sys_openat fs/open.c:1352 [inline] __se_sys_openat fs/open.c:1347 [inline] __x64_sys_openat+0x135/0x160 fs/open.c:1347 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fd3f4de4407 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:00007fffbff29ac0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fd3f4d58880 RCX: 00007fd3f4de4407 RDX: 0000000000000000 RSI: 00007fffbff2af1b RDI: ffffffffffffff9c RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00007fffbff29d10 R14: 00007fd3f5035000 R15: 000055d44eb194d8 Allocated by task 4777: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:53 ____kasan_kmalloc mm/kasan/common.c:375 [inline] __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:384 kmalloc include/linux/slab.h:563 [inline] kzalloc include/linux/slab.h:699 [inline] em28xx_v4l2_init+0xf5/0x2d90 drivers/media/usb/em28xx/em28xx-video.c:2538 em28xx_init_extension+0x118/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1116 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292 process_scheduled_works kernel/workqueue.c:2355 [inline] worker_thread+0xdd1/0x12a0 kernel/workqueue.c:2444 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Freed by task 4777: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:53 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237 kasan_slab_free include/linux/kasan.h:177 [inline] slab_free_hook mm/slub.c:1729 [inline] slab_free_freelist_hook+0x133/0x1b0 mm/slub.c:1755 slab_free mm/slub.c:3687 [inline] __kmem_cache_free+0xb6/0x200 mm/slub.c:3700 em28xx_free_v4l2 drivers/media/usb/em28xx/em28xx-video.c:2118 [inline] kref_put include/linux/kref.h:65 [inline] em28xx_v4l2_init+0x15f7/0x2d90 drivers/media/usb/em28xx/em28xx-video.c:2907 em28xx_init_extension+0x118/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1116 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292 process_scheduled_works kernel/workqueue.c:2355 [inline] worker_thread+0xdd1/0x12a0 kernel/workqueue.c:2444 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Last potentially related work creation: kasan_save_stack+0x3a/0x60 mm/kasan/common.c:46 __kasan_record_aux_stack+0xb2/0xc0 mm/kasan/generic.c:486 insert_work+0x54/0x3c0 kernel/workqueue.c:1361 __queue_work+0xae2/0xee0 kernel/workqueue.c:1520 queue_work_on+0x124/0x1f0 kernel/workqueue.c:1548 kref_put include/linux/kref.h:65 [inline] sg_release+0x1d0/0x2c0 drivers/scsi/sg.c:404 __fput+0x20a/0x8b0 fs/file_table.c:320 task_work_run+0x1d0/0x260 kernel/task_work.c:203 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 Second to last potentially related work creation: kasan_save_stack+0x3a/0x60 mm/kasan/common.c:46 __kasan_record_aux_stack+0xb2/0xc0 mm/kasan/generic.c:486 insert_work+0x54/0x3c0 kernel/workqueue.c:1361 __queue_work+0xae2/0xee0 kernel/workqueue.c:1520 queue_work_on+0x124/0x1f0 kernel/workqueue.c:1548 kref_put include/linux/kref.h:65 [inline] sg_release+0x1d0/0x2c0 drivers/scsi/sg.c:404 __fput+0x20a/0x8b0 fs/file_table.c:320 task_work_run+0x1d0/0x260 kernel/task_work.c:203 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x68/0xd2 The buggy address belongs to the object at ffff88807d9e4000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 2024 bytes inside of 8192-byte region [ffff88807d9e4000, ffff88807d9e6000) The buggy address belongs to the physical page: page:ffffea0001f67800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7d9e0 head:ffffea0001f67800 order:3 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 ffffea0001583800 dead000000000002 ffff888017442280 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4280, tgid 4280 (syz-executor), ts 73328330558, free_ts 73200080928 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2560 prep_new_page mm/page_alloc.c:2567 [inline] get_page_from_freelist+0x206b/0x2180 mm/page_alloc.c:4358 __alloc_pages+0x1ec/0x4f0 mm/page_alloc.c:5658 alloc_slab_page+0x5d/0x180 mm/slub.c:1799 allocate_slab mm/slub.c:1944 [inline] new_slab+0x87/0x2d0 mm/slub.c:1997 ___slab_alloc+0xbc5/0x1240 mm/slub.c:3154 __slab_alloc mm/slub.c:3240 [inline] slab_alloc_node mm/slub.c:3325 [inline] __kmem_cache_alloc_node+0x126/0x270 mm/slub.c:3398 __do_kmalloc_node mm/slab_common.c:935 [inline] __kmalloc_node+0xa2/0x240 mm/slab_common.c:943 kmalloc_node include/linux/slab.h:589 [inline] kvmalloc_node+0x6c/0x180 mm/util.c:581 kvmalloc include/linux/slab.h:716 [inline] kvmalloc_array include/linux/slab.h:734 [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+0x35f/0x6a0 net/sched/sch_generic.c:870 qdisc_create_dflt+0x11a/0x490 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:2465 [inline] attach_default_qdiscs net/sched/sch_generic.c:1194 [inline] dev_activate+0x392/0x1150 net/sched/sch_generic.c:1253 __dev_open+0x343/0x430 net/core/dev.c:1510 __dev_change_flags+0x1e4/0x6a0 net/core/dev.c:8676 dev_change_flags+0x78/0x1a0 net/core/dev.c:8748 do_setlink+0xbc7/0x29c0 net/core/rtnetlink.c:2837 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1487 [inline] free_pcp_prepare mm/page_alloc.c:1537 [inline] free_unref_page_prepare+0x8e5/0x9e0 mm/page_alloc.c:3414 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3509 qlink_free mm/kasan/quarantine.c:168 [inline] qlist_free_all+0x76/0xe0 mm/kasan/quarantine.c:187 kasan_quarantine_reduce+0x144/0x160 mm/kasan/quarantine.c:294 __kasan_slab_alloc+0x1e/0x80 mm/kasan/common.c:306 kasan_slab_alloc include/linux/kasan.h:201 [inline] slab_post_alloc_hook+0x4b/0x490 mm/slab.h:737 slab_alloc_node mm/slub.c:3359 [inline] __kmem_cache_alloc_node+0x19d/0x270 mm/slub.c:3398 kmalloc_trace+0x26/0xe0 mm/slab_common.c:1026 kmalloc include/linux/slab.h:563 [inline] kzalloc include/linux/slab.h:699 [inline] mca_alloc net/ipv6/mcast.c:880 [inline] __ipv6_dev_mc_inc+0x3fb/0xac0 net/ipv6/mcast.c:935 addrconf_join_solict net/ipv6/addrconf.c:2197 [inline] addrconf_dad_begin net/ipv6/addrconf.c:4039 [inline] addrconf_dad_work+0x3b8/0x1500 net/ipv6/addrconf.c:4164 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Memory state around the buggy address: ffff88807d9e4680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88807d9e4700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88807d9e4780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88807d9e4800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88807d9e4880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================