KASAN: use-after-free Read in ax88172a_unbind

[syzbot <syzbot+4cd84f527bf4a10fc9c1@syzkaller.appspotmail.com>]

Hello,

syzbot found the following crash on:

HEAD commit:    32b5e2b2 usb: gadget: add raw-gadget interface
git tree:       https://github.com/google/kasan.git usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=12d808a6e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d88612251f7691bd
dashboard link: https://syzkaller.appspot.com/bug?extid=4cd84f527bf4a10fc9c1
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=107034a2e00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12da42dae00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+4cd84f527bf4a10fc9c1@syzkaller.appspotmail.com

usb 1-1: USB disconnect, device number 2
asix 1-1:0.147 eth1: unregister 'asix' usb-dummy_hcd.0-1, ASIX AX88172A USB  
2.0 Ethernet
==================================================================
BUG: KASAN: use-after-free in ax88172a_remove_mdio  
drivers/net/usb/ax88172a.c:123 [inline]
BUG: KASAN: use-after-free in ax88172a_unbind+0x76/0xed  
drivers/net/usb/ax88172a.c:274
Read of size 8 at addr ffff8881d15e9100 by task kworker/0:2/102

CPU: 0 PID: 102 Comm: kworker/0:2 Not tainted 5.4.0-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+0x36/0x50 mm/kasan/report.c:374
  __kasan_report.cold+0x1a/0x33 mm/kasan/report.c:506
  kasan_report+0xe/0x20 mm/kasan/common.c:634
  ax88172a_remove_mdio drivers/net/usb/ax88172a.c:123 [inline]
  ax88172a_unbind+0x76/0xed drivers/net/usb/ax88172a.c:274
  usbnet_disconnect+0x145/0x270 drivers/net/usb/usbnet.c:1618
  usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
  __device_release_driver drivers/base/dd.c:1134 [inline]
  device_release_driver_internal+0x42f/0x500 drivers/base/dd.c:1165
  bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:532
  device_del+0x481/0xd30 drivers/base/core.c:2664
  usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
  usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2200
  hub_port_connect drivers/usb/core/hub.c:5035 [inline]
  hub_port_connect_change drivers/usb/core/hub.c:5324 [inline]
  port_event drivers/usb/core/hub.c:5470 [inline]
  hub_event+0x1753/0x3860 drivers/usb/core/hub.c:5552
  process_one_work+0x92b/0x1530 kernel/workqueue.c:2264
  worker_thread+0x96/0xe20 kernel/workqueue.c:2410
  kthread+0x318/0x420 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 83:
  save_stack+0x1b/0x80 mm/kasan/common.c:69
  set_track mm/kasan/common.c:77 [inline]
  __kasan_kmalloc mm/kasan/common.c:510 [inline]
  __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:483
  kmalloc include/linux/slab.h:556 [inline]
  kzalloc include/linux/slab.h:690 [inline]
  ax88172a_bind+0x9f/0x7a2 drivers/net/usb/ax88172a.c:191
  usbnet_probe+0xb43/0x2470 drivers/net/usb/usbnet.c:1737
  usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
  really_probe+0x281/0x6d0 drivers/base/dd.c:548
  driver_probe_device+0x104/0x210 drivers/base/dd.c:721
  __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
  bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
  __device_attach+0x217/0x360 drivers/base/dd.c:894
  bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
  device_add+0x1480/0x1c20 drivers/base/core.c:2487
  usb_set_configuration+0xe67/0x1740 drivers/usb/core/message.c:2023
  generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
  usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266
  really_probe+0x281/0x6d0 drivers/base/dd.c:548
  driver_probe_device+0x104/0x210 drivers/base/dd.c:721
  __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
  bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
  __device_attach+0x217/0x360 drivers/base/dd.c:894
  bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
  device_add+0x1480/0x1c20 drivers/base/core.c:2487
  usb_new_device.cold+0x6a4/0xe79 drivers/usb/core/hub.c:2537
  hub_port_connect drivers/usb/core/hub.c:5184 [inline]
  hub_port_connect_change drivers/usb/core/hub.c:5324 [inline]
  port_event drivers/usb/core/hub.c:5470 [inline]
  hub_event+0x1e59/0x3860 drivers/usb/core/hub.c:5552
  process_one_work+0x92b/0x1530 kernel/workqueue.c:2264
  worker_thread+0x96/0xe20 kernel/workqueue.c:2410
  kthread+0x318/0x420 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 83:
  save_stack+0x1b/0x80 mm/kasan/common.c:69
  set_track mm/kasan/common.c:77 [inline]
  kasan_set_free_info mm/kasan/common.c:332 [inline]
  __kasan_slab_free+0x130/0x180 mm/kasan/common.c:471
  slab_free_hook mm/slub.c:1424 [inline]
  slab_free_freelist_hook mm/slub.c:1457 [inline]
  slab_free mm/slub.c:3004 [inline]
  kfree+0xdc/0x310 mm/slub.c:3956
  ax88172a_bind.cold+0x4d/0x1e8 drivers/net/usb/ax88172a.c:250
  usbnet_probe+0xb43/0x2470 drivers/net/usb/usbnet.c:1737
  usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
  really_probe+0x281/0x6d0 drivers/base/dd.c:548
  driver_probe_device+0x104/0x210 drivers/base/dd.c:721
  __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
  bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
  __device_attach+0x217/0x360 drivers/base/dd.c:894
  bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
  device_add+0x1480/0x1c20 drivers/base/core.c:2487
  usb_set_configuration+0xe67/0x1740 drivers/usb/core/message.c:2023
  generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
  usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266
  really_probe+0x281/0x6d0 drivers/base/dd.c:548
  driver_probe_device+0x104/0x210 drivers/base/dd.c:721
  __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
  bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
  __device_attach+0x217/0x360 drivers/base/dd.c:894
  bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
  device_add+0x1480/0x1c20 drivers/base/core.c:2487
  usb_new_device.cold+0x6a4/0xe79 drivers/usb/core/hub.c:2537
  hub_port_connect drivers/usb/core/hub.c:5184 [inline]
  hub_port_connect_change drivers/usb/core/hub.c:5324 [inline]
  port_event drivers/usb/core/hub.c:5470 [inline]
  hub_event+0x1e59/0x3860 drivers/usb/core/hub.c:5552
  process_one_work+0x92b/0x1530 kernel/workqueue.c:2264
  worker_thread+0x96/0xe20 kernel/workqueue.c:2410
  kthread+0x318/0x420 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff8881d15e9100
  which belongs to the cache kmalloc-64 of size 64
The buggy address is located 0 bytes inside of
  64-byte region [ffff8881d15e9100, ffff8881d15e9140)
The buggy address belongs to the page:
page:ffffea0007457a40 refcount:1 mapcount:0 mapping:ffff8881da003180  
index:0x0
raw: 0200000000000200 ffffea00074686c0 0000000d0000000d ffff8881da003180
raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8881d15e9000: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
  ffff8881d15e9080: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> ffff8881d15e9100: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                    ^
  ffff8881d15e9180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
  ffff8881d15e9200: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================


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