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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 ffff8881cd21c8c8 by task v4l_id/354

CPU: 1 PID: 354 Comm: v4l_id Not tainted 5.8.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xf6/0x16e lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x415 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x37/0x7c mm/kasan/report.c:530
 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+0x11a/0x570 drivers/media/usb/em28xx/em28xx-video.c:2163
 v4l2_open+0x20f/0x3d0 drivers/media/v4l2-core/v4l2-dev.c:423
 chrdev_open+0x219/0x5c0 fs/char_dev.c:414
 do_dentry_open+0x4fd/0x1170 fs/open.c:828
 do_open fs/namei.c:3243 [inline]
 path_openat+0x1cc5/0x26c0 fs/namei.c:3360
 do_filp_open+0x192/0x260 fs/namei.c:3387
 do_sys_openat2+0x585/0x7d0 fs/open.c:1179
 do_sys_open+0xc3/0x140 fs/open.c:1195
 do_syscall_64+0x50/0x90 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f9b8fd85840
Code: Bad RIP value.
RSP: 002b:00007ffe56bbd5a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007ffe56bbd718 RCX: 00007f9b8fd85840
RDX: 00007f9b8fd71ea0 RSI: 0000000000000000 RDI: 00007ffe56bbdf23
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000565511e988d0
R13: 00007ffe56bbd710 R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea0007348700 refcount:0 mapcount:-128 mapping:0000000000000000 index:0x0
flags: 0x200000000000000()
raw: 0200000000000000 ffff88821fffabd0 ffff88821fffabd0 0000000000000000
raw: 0000000000000000 0000000000000002 00000000ffffff7f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881cd21c780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881cd21c800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8881cd21c880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff8881cd21c900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881cd21c980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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