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BUG: KASAN: use-after-free in v4l2_fh_init drivers/media/v4l2-core/v4l2-fh.c:25 [inline]
BUG: KASAN: use-after-free in v4l2_fh_open+0xc6/0x430 drivers/media/v4l2-core/v4l2-fh.c:63
Read of size 8 at addr ffff888060478900 by task v4l_id/5295

CPU: 1 PID: 5295 Comm: v4l_id Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 v4l2_fh_init drivers/media/v4l2-core/v4l2-fh.c:25 [inline]
 v4l2_fh_open+0xc6/0x430 drivers/media/v4l2-core/v4l2-fh.c:63
 em28xx_v4l2_open+0x152/0x990 drivers/media/usb/em28xx/em28xx-video.c:2163
 v4l2_open+0x20b/0x360 drivers/media/v4l2-core/v4l2-dev.c:427
 chrdev_open+0x5c5/0x6a0 fs/char_dev.c:414
 do_dentry_open+0x7ff/0xf80 fs/open.c:826
 do_open fs/namei.c:3616 [inline]
 path_openat+0x26f5/0x2fa0 fs/namei.c:3750
 do_filp_open+0x1e2/0x410 fs/namei.c:3777
 do_sys_openat2+0x150/0x4b0 fs/open.c:1255
 do_sys_open fs/open.c:1271 [inline]
 __do_sys_openat fs/open.c:1287 [inline]
 __se_sys_openat fs/open.c:1282 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1282
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f708ff60407
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:00007ffff2b8a8c0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f708fe72880 RCX: 00007f708ff60407
RDX: 0000000000000000 RSI: 00007ffff2b8af1c RDI: ffffffffffffff9c
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 00007ffff2b8ab10 R14: 00007f70906ee000 R15: 000055da67f424d8
 </TASK>

The buggy address belongs to the page:
page:ffffea0001811e00 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x60478
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea00017f4308 ffff8880b90409f0 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x102800(GFP_NOWAIT|__GFP_NOWARN|__GFP_HARDWALL), pid 5273, ts 125128657695, free_ts 125128662732
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x1bbd/0x1ca0 mm/page_alloc.c:4192
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
 stack_depot_save+0x342/0x440 lib/stackdepot.c:302
 kasan_save_stack+0x4b/0x60 mm/kasan/common.c:40
 kasan_record_aux_stack+0xb8/0x100 mm/kasan/generic.c:348
 insert_work+0x54/0x3d0 kernel/workqueue.c:1366
 __queue_work+0x9c5/0xd50 kernel/workqueue.c:1532
 queue_work_on+0x124/0x1f0 kernel/workqueue.c:1559
 queue_work include/linux/workqueue.h:512 [inline]
 loop_queue_work drivers/block/loop.c:1068 [inline]
 loop_queue_rq+0x9d8/0xac0 drivers/block/loop.c:2202
 __blk_mq_issue_directly block/blk-mq.c:2015 [inline]
 __blk_mq_try_issue_directly+0x497/0x820 block/blk-mq.c:2071
 blk_mq_try_issue_directly+0xaf/0x270 block/blk-mq.c:2102
 blk_mq_submit_bio+0xfa1/0x1820 block/blk-mq.c:-1
 __submit_bio+0x7d1/0x820 block/blk-core.c:917
 __submit_bio_noacct_mq block/blk-core.c:997 [inline]
 submit_bio_noacct+0x6b0/0x800 block/blk-core.c:1027
 submit_bio+0x2c1/0x560 block/blk-core.c:1089
 submit_bh fs/buffer.c:3062 [inline]
 __sync_dirty_buffer+0x237/0x370 fs/buffer.c:3157
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page+0x8f/0x2a0 mm/page_alloc.c:3396
 stack_depot_save+0x418/0x440 lib/stackdepot.c:335
 kasan_save_stack+0x4b/0x60 mm/kasan/common.c:40
 kasan_record_aux_stack+0xb8/0x100 mm/kasan/generic.c:348
 insert_work+0x54/0x3d0 kernel/workqueue.c:1366
 __queue_work+0x9c5/0xd50 kernel/workqueue.c:1532
 queue_work_on+0x124/0x1f0 kernel/workqueue.c:1559
 queue_work include/linux/workqueue.h:512 [inline]
 loop_queue_work drivers/block/loop.c:1068 [inline]
 loop_queue_rq+0x9d8/0xac0 drivers/block/loop.c:2202
 __blk_mq_issue_directly block/blk-mq.c:2015 [inline]
 __blk_mq_try_issue_directly+0x497/0x820 block/blk-mq.c:2071
 blk_mq_try_issue_directly+0xaf/0x270 block/blk-mq.c:2102
 blk_mq_submit_bio+0xfa1/0x1820 block/blk-mq.c:-1
 __submit_bio+0x7d1/0x820 block/blk-core.c:917
 __submit_bio_noacct_mq block/blk-core.c:997 [inline]
 submit_bio_noacct+0x6b0/0x800 block/blk-core.c:1027
 submit_bio+0x2c1/0x560 block/blk-core.c:1089
 submit_bh fs/buffer.c:3062 [inline]
 __sync_dirty_buffer+0x237/0x370 fs/buffer.c:3157

Memory state around the buggy address:
 ffff888060478800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888060478880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888060478900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888060478980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888060478a00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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