KASAN: use-after-free Read in em28xx_release_resources

[syzbot <syzbot+83803be25e647b7e40b0@syzkaller.appspotmail.com>]

Hello,

syzbot found the following crash on:

HEAD commit:    806d8acc USB: dummy-hcd: use configurable endpoint naming ..
git tree:       https://github.com/google/kasan.git usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=161ad202100000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d800e9bad158025f
dashboard link: https://syzkaller.appspot.com/bug?extid=83803be25e647b7e40b0
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+83803be25e647b7e40b0@syzkaller.appspotmail.com

em28xx 2-1:0.63: Closing input extension
==================================================================
BUG: KASAN: use-after-free in media_device_unregister drivers/media/mc/mc-device.c:822 [inline]
BUG: KASAN: use-after-free in media_device_unregister+0x564/0x5d0 drivers/media/mc/mc-device.c:800
Read of size 8 at addr ffff8881ccf74210 by task kworker/1:7/3751

CPU: 1 PID: 3751 Comm: kworker/1:7 Not tainted 5.7.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xef/0x16e lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x314 mm/kasan/report.c:382
 __kasan_report.cold+0x37/0x92 mm/kasan/report.c:511
 kasan_report+0x33/0x50 mm/kasan/common.c:625
 media_device_unregister drivers/media/mc/mc-device.c:822 [inline]
 media_device_unregister+0x564/0x5d0 drivers/media/mc/mc-device.c:800
 em28xx_unregister_media_device drivers/media/usb/em28xx/em28xx-cards.c:3392 [inline]
 em28xx_release_resources+0xaf/0x254 drivers/media/usb/em28xx/em28xx-cards.c:3413
 em28xx_usb_disconnect.cold+0x18b/0x284 drivers/media/usb/em28xx/em28xx-cards.c:4072
 usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:436
 __device_release_driver drivers/base/dd.c:1110 [inline]
 device_release_driver_internal+0x432/0x500 drivers/base/dd.c:1141
 bus_remove_device+0x2eb/0x5a0 drivers/base/bus.c:533
 device_del+0x481/0xd30 drivers/base/core.c:2715
 usb_disable_device+0x23d/0x790 drivers/usb/core/message.c:1245
 usb_disconnect+0x293/0x900 drivers/usb/core/hub.c:2216
 hub_port_connect drivers/usb/core/hub.c:5058 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5347 [inline]
 port_event drivers/usb/core/hub.c:5493 [inline]
 hub_event+0x1abf/0x43c0 drivers/usb/core/hub.c:5575
 process_one_work+0x965/0x1630 kernel/workqueue.c:2268
 process_scheduled_works kernel/workqueue.c:2330 [inline]
 worker_thread+0x7ab/0xe20 kernel/workqueue.c:2416
 kthread+0x326/0x430 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351

The buggy address belongs to the page:
page:ffffea000733dd00 refcount:0 mapcount:-128 mapping:00000000f4330ebd index:0x0
flags: 0x200000000000000()
raw: 0200000000000000 ffffea00071b0808 ffff88821fffabd0 0000000000000000
raw: 0000000000000000 0000000000000002 00000000ffffff7f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881ccf74100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881ccf74180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8881ccf74200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                         ^
 ffff8881ccf74280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881ccf74300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


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