syzbot

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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 ffff8880768b0860 by task v4l_id/6210

CPU: 1 UID: 0 PID: 6210 Comm: v4l_id Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 __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/0x1d0 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+0x6d8/0x1660 fs/open.c:947
 vfs_open+0x82/0x3f0 fs/open.c:1079
 do_open fs/namei.c:4699 [inline]
 path_openat+0x208c/0x31a0 fs/namei.c:4858
 do_file_open+0x20e/0x430 fs/namei.c:4887
 do_sys_openat2+0x10d/0x1e0 fs/open.c:1364
 do_sys_open fs/open.c:1370 [inline]
 __do_sys_openat fs/open.c:1386 [inline]
 __se_sys_openat fs/open.c:1381 [inline]
 __x64_sys_openat+0x12d/0x210 fs/open.c:1381
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb25a2a7407
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:00007ffd627c5cb0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fb25a984880 RCX: 00007fb25a2a7407
RDX: 0000000000000000 RSI: 00007ffd627c6f1b RDI: ffffffffffffff9c
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 00007ffd627c5f00 R14: 00007fb25aaeb000 R15: 00005579c997f4d8
 </TASK>

Allocated by task 9:
 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:950 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 em28xx_v4l2_init.cold+0x94/0x3a40 drivers/media/usb/em28xx/em28xx-video.c:2707
 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+0xa0e/0x1980 kernel/workqueue.c:3302
 process_scheduled_works kernel/workqueue.c:3385 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3466
 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 9:
 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:2689 [inline]
 slab_free mm/slub.c:6250 [inline]
 kfree+0x223/0x6c0 mm/slub.c:6565
 kref_put.isra.0+0x53/0x75 include/linux/kref.h:65
 em28xx_v4l2_init.cold+0x280/0x3a40 drivers/media/usb/em28xx/em28xx-video.c:3078
 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+0xa0e/0x1980 kernel/workqueue.c:3302
 process_scheduled_works kernel/workqueue.c:3385 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3466
 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 ffff8880768b0000
 which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 2144 bytes inside of
 freed 8192-byte region [ffff8880768b0000, ffff8880768b2000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x768b0
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 ffff88813fe35280 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800020002 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813fe35280 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 5677, tgid 5677 (syz-executor), ts 84365375689, free_ts 84283669570
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x153/0x170 mm/page_alloc.c:1858
 prep_new_page mm/page_alloc.c:1866 [inline]
 get_page_from_freelist+0x11a6/0x33b0 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x27c/0x2bc0 mm/page_alloc.c:5226
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab mm/slub.c:3467 [inline]
 new_slab+0xa6/0x6c0 mm/slub.c:3525
 refill_objects+0x277/0x420 mm/slub.c:7255
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x375/0x650 mm/slub.c:4651
 alloc_from_pcs mm/slub.c:4749 [inline]
 slab_alloc_node mm/slub.c:4883 [inline]
 __kmalloc_cache_noprof+0x493/0x6f0 mm/slub.c:5414
 kmalloc_noprof include/linux/slab.h:950 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 mr_table_alloc+0x61/0x3e0 net/ipv4/ipmr_base.c:55
 ip6mr_new_table net/ipv6/ip6mr.c:401 [inline]
 ip6mr_new_table net/ipv6/ip6mr.c:393 [inline]
 ip6mr_rules_init net/ipv6/ip6mr.c:249 [inline]
 ip6mr_net_init net/ipv6/ip6mr.c:1334 [inline]
 ip6mr_net_init+0x341/0x4d0 net/ipv6/ip6mr.c:1326
 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:3243
 __do_sys_unshare kernel/fork.c:3317 [inline]
 __se_sys_unshare kernel/fork.c:3315 [inline]
 __x64_sys_unshare+0x31/0x40 kernel/fork.c:3315
page last free pid 5662 tgid 5662 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1402 [inline]
 __free_frozen_pages+0x747/0x1040 mm/page_alloc.c:2943
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4569 [inline]
 slab_alloc_node mm/slub.c:4898 [inline]
 kmem_cache_alloc_noprof+0x241/0x6e0 mm/slub.c:4905
 __kernfs_new_node+0xd2/0x9f0 fs/kernfs/dir.c:664
 kernfs_new_node+0x11b/0x1a0 fs/kernfs/dir.c:748
 __kernfs_create_file+0x53/0x350 fs/kernfs/file.c:1057
 sysfs_add_file_mode_ns+0x207/0x3c0 fs/sysfs/file.c:313
 create_files fs/sysfs/group.c:82 [inline]
 internal_create_group+0x593/0xf40 fs/sysfs/group.c:189
 internal_create_groups+0x9d/0x150 fs/sysfs/group.c:229
 device_add_groups drivers/base/core.c:2837 [inline]
 device_add_attrs drivers/base/core.c:2912 [inline]
 device_add+0xf5b/0x1950 drivers/base/core.c:3645
 netdev_register_kobject+0x1a9/0x3d0 net/core/net-sysfs.c:2343
 register_netdevice+0x151c/0x24b0 net/core/dev.c:11420
 register_netdev+0x34/0x50 net/core/dev.c:11536
 vti6_init_net+0x2c7/0x440 net/ipv6/ip6_vti.c:1158

Memory state around the buggy address:
 ffff8880768b0700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880768b0780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880768b0800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff8880768b0880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880768b0900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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