syzbot

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BUG: KASAN: slab-use-after-free in v4l2_open+0x395/0x3a0 drivers/media/v4l2-core/v4l2-dev.c:444
Read of size 4 at addr ffff88807cc0c858 by task v4l_id/6106

CPU: 1 UID: 0 PID: 6106 Comm: v4l_id Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 v4l2_open+0x395/0x3a0 drivers/media/v4l2-core/v4l2-dev.c:444
 chrdev_open+0x4cd/0x5e0 fs/char_dev.c:411
 do_dentry_open+0x785/0x14e0 fs/open.c:949
 vfs_open+0x3b/0x340 fs/open.c:1081
 do_open fs/namei.c:4693 [inline]
 path_openat+0x2e08/0x3860 fs/namei.c:4852
 do_file_open+0x23e/0x4a0 fs/namei.c:4881
 do_sys_openat2+0x113/0x200 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+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f07658a7407
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:00007fffa6721d10 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f0765fad880 RCX: 00007f07658a7407
RDX: 0000000000000000 RSI: 00007fffa6722f1c RDI: ffffffffffffff9c
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 00007fffa6721f60 R14: 00007f0766114000 R15: 00005644e71564d8
 </TASK>

Allocated by task 5846:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5412
 kmalloc_noprof include/linux/slab.h:950 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 em28xx_v4l2_init+0x10b/0x2e70 drivers/media/usb/em28xx/em28xx-video.c:2538
 em28xx_init_extension+0x120/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1117
 process_one_work+0x9a3/0x1710 kernel/workqueue.c:3288
 process_scheduled_works kernel/workqueue.c:3379 [inline]
 worker_thread+0xba8/0x11e0 kernel/workqueue.c:3465
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 5846:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/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:6242 [inline]
 kfree+0x1c5/0x640 mm/slub.c:6557
 em28xx_free_v4l2 drivers/media/usb/em28xx/em28xx-video.c:2118 [inline]
 kref_put include/linux/kref.h:65 [inline]
 em28xx_v4l2_init+0x1683/0x2e70 drivers/media/usb/em28xx/em28xx-video.c:2907
 em28xx_init_extension+0x120/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1117
 process_one_work+0x9a3/0x1710 kernel/workqueue.c:3288
 process_scheduled_works kernel/workqueue.c:3379 [inline]
 worker_thread+0xba8/0x11e0 kernel/workqueue.c:3465
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 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 ffff88807cc0c000
 which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 2136 bytes inside of
 freed 8192-byte region [ffff88807cc0c000, ffff88807cc0e000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7cc08
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 ffff88813ff1d280 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800020002 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813ff1d280 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 5862, tgid 5862 (syz-executor), ts 94017172522, free_ts 92254383191
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1859
 prep_new_page mm/page_alloc.c:1867 [inline]
 get_page_from_freelist+0x2418/0x24b0 mm/page_alloc.c:3926
 __alloc_frozen_pages_noprof+0x233/0x3d0 mm/page_alloc.c:5213
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3467
 new_slab mm/slub.c:3525 [inline]
 refill_objects+0x339/0x3d0 mm/slub.c:7247
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4651
 alloc_from_pcs mm/slub.c:4749 [inline]
 slab_alloc_node mm/slub.c:4883 [inline]
 __do_kmalloc_node mm/slub.c:5291 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5304
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 cache_create_net+0x98/0x230 net/sunrpc/cache.c:1760
 rsc_cache_create_net net/sunrpc/auth_gss/svcauth_gss.c:2054 [inline]
 gss_svc_init_net+0x58/0x570 net/sunrpc/auth_gss/svcauth_gss.c:2082
 ops_init+0x35c/0x5c0 net/core/net_namespace.c:137
 setup_net+0x118/0x340 net/core/net_namespace.c:446
 copy_net_ns+0x50e/0x730 net/core/net_namespace.c:581
 create_new_namespaces+0x3e7/0x6a0 kernel/nsproxy.c:130
 unshare_nsproxy_namespaces+0x11a/0x160 kernel/nsproxy.c:226
 ksys_unshare+0x521/0x980 kernel/fork.c:3239
 __do_sys_unshare kernel/fork.c:3313 [inline]
 __se_sys_unshare kernel/fork.c:3311 [inline]
 __x64_sys_unshare+0x38/0x50 kernel/fork.c:3311
page last free pid 5837 tgid 5835 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1403 [inline]
 __free_frozen_pages+0xbc7/0xd30 mm/page_alloc.c:2944
 __folio_put+0x4a2/0x580 mm/swap.c:112
 folio_put include/linux/mm.h:2092 [inline]
 put_page include/linux/mm.h:2161 [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+0x62f/0xa80 net/core/skbuff.c:1111
 skb_release_all net/core/skbuff.c:1192 [inline]
 __kfree_skb+0x5d/0x210 net/core/skbuff.c:1206
 tcp_clean_rtx_queue net/ipv4/tcp_input.c:3698 [inline]
 tcp_ack+0x2818/0x7dd0 net/ipv4/tcp_input.c:4366
 tcp_rcv_established+0xbac/0x26b0 net/ipv4/tcp_input.c:6642
 tcp_v4_do_rcv+0x964/0x13c0 net/ipv4/tcp_ipv4.c:1866
 tcp_v4_rcv+0x2825/0x31f0 net/ipv4/tcp_ipv4.c:2263
 ip_protocol_deliver_rcu+0x221/0x440 net/ipv4/ip_input.c:207
 ip_local_deliver_finish+0x3bb/0x6f0 net/ipv4/ip_input.c:241
 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:318
 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:318
 __netif_receive_skb_one_core net/core/dev.c:6182 [inline]
 __netif_receive_skb net/core/dev.c:6295 [inline]
 process_backlog+0xaa3/0x1950 net/core/dev.c:6646
 __napi_poll+0xae/0x340 net/core/dev.c:7710
 napi_poll net/core/dev.c:7773 [inline]
 net_rx_action+0x627/0xf70 net/core/dev.c:7930
 handle_softirqs+0x22a/0x840 kernel/softirq.c:626

Memory state around the buggy address:
 ffff88807cc0c700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807cc0c780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807cc0c800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff88807cc0c880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88807cc0c900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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