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BUG: KASAN: use-after-free in v4l2_fh_init+0x279/0x2c0 drivers/media/v4l2-core/v4l2-fh.c:25
Read of size 8 at addr ffff8880316fc8b8 by task v4l_id/8745

CPU: 0 PID: 8745 Comm: v4l_id Not tainted 5.13.0-rc2-next-20210518-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x13e/0x1d6 lib/dump_stack.c:129
 print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:233
 __kasan_report mm/kasan/report.c:419 [inline]
 kasan_report.cold+0x83/0xdf mm/kasan/report.c:436
 v4l2_fh_init+0x279/0x2c0 drivers/media/v4l2-core/v4l2-fh.c:25
 v4l2_fh_open+0x88/0xc0 drivers/media/v4l2-core/v4l2-fh.c:63
 em28xx_v4l2_open+0x11c/0x570 drivers/media/usb/em28xx/em28xx-video.c:2163
 v4l2_open+0x21c/0x3f0 drivers/media/v4l2-core/v4l2-dev.c:429
 chrdev_open+0x266/0x770 fs/char_dev.c:414
 do_dentry_open+0x4b9/0x11c0 fs/open.c:826
 do_open fs/namei.c:3361 [inline]
 path_openat+0x1c09/0x27d0 fs/namei.c:3494
 do_filp_open+0x190/0x3d0 fs/namei.c:3521
 do_sys_openat2+0x16d/0x420 fs/open.c:1196
 do_sys_open fs/open.c:1212 [inline]
 __do_sys_open fs/open.c:1220 [inline]
 __se_sys_open fs/open.c:1216 [inline]
 __x64_sys_open+0x119/0x1c0 fs/open.c:1216
 do_syscall_64+0x31/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f74678c6840
Code: 73 01 c3 48 8b 0d 68 77 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 89 bb 20 00 00 75 10 b8 02 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 1e f6 ff ff 48 89 04 24
RSP: 002b:00007fff387ef948 EFLAGS: 00000246
 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007fff387efab8 RCX: 00007f74678c6840
RDX: 00007f74678b2ea0 RSI: 0000000000000000 RDI: 00007fff387f0f1d
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 000055bb14d828d0
R13: 00007fff387efab0 R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea0000c5bf00 refcount:0 mapcount:-128 mapping:0000000000000000 index:0x0 pfn:0x316fc
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffff88813fffb910 ffffea0000b63308 0000000000000000
raw: 0000000000000000 0000000000000002 00000000ffffff7f 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 0x40dc0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO), pid 8566, ts 115359279942, free_ts 115546435685
 prep_new_page mm/page_alloc.c:2377 [inline]
 get_page_from_freelist+0x125c/0x2ed0 mm/page_alloc.c:4038
 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5239
 alloc_pages+0x18c/0x2a0 mm/mempolicy.c:2272
 kmalloc_order+0x34/0xf0 mm/slab_common.c:954
 kmalloc_order_trace+0x14/0x120 mm/slab_common.c:970
 kmalloc_large include/linux/slab.h:519 [inline]
 kmalloc include/linux/slab.h:583 [inline]
 kzalloc include/linux/slab.h:720 [inline]
 em28xx_v4l2_init drivers/media/usb/em28xx/em28xx-video.c:2542 [inline]
 em28xx_v4l2_init.cold+0x67/0x3265 drivers/media/usb/em28xx/em28xx-video.c:2520
 em28xx_init_extension+0x12f/0x1f0 drivers/media/usb/em28xx/em28xx-core.c:1126
 request_module_async+0x5d/0x70 drivers/media/usb/em28xx/em28xx-cards.c:3410
 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
 kthread+0x3b1/0x4a0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1305 [inline]
 __free_pages_ok+0x4cb/0xf30 mm/page_alloc.c:1586
 kref_put.isra.0+0x6f/0xa0 include/linux/kref.h:65
 em28xx_v4l2_init drivers/media/usb/em28xx/em28xx-video.c:2911 [inline]
 em28xx_v4l2_init.cold+0x238/0x3265 drivers/media/usb/em28xx/em28xx-video.c:2520
 em28xx_init_extension+0x12f/0x1f0 drivers/media/usb/em28xx/em28xx-core.c:1126
 request_module_async+0x5d/0x70 drivers/media/usb/em28xx/em28xx-cards.c:3410
 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
 kthread+0x3b1/0x4a0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Memory state around the buggy address:
 ffff8880316fc780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880316fc800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880316fc880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                        ^
 ffff8880316fc900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880316fc980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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