Message-ID: <0000000000003ee3610599d20096@google.com>
Date:   Mon, 16 Dec 2019 05:15:09 -0800
From:   syzbot <syzbot+0b0095300dfeb8a83dc8@...kaller.appspotmail.com>
To:     andreyknvl@...gle.com, laurent.pinchart@...asonboard.com,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        linux-usb@...r.kernel.org, mchehab@...nel.org,
        sakari.ailus@...ux.intel.com, syzkaller-bugs@...glegroups.com
Subject: KASAN: use-after-free Read in __media_entity_remove_links

Hello,

syzbot found the following crash on:

HEAD commit:    4cc037ec 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=104e177ee00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e9c2b6de462bc469
dashboard link: https://syzkaller.appspot.com/bug?extid=0b0095300dfeb8a83dc8
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=117f2fb1e00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16842d2ee00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+0b0095300dfeb8a83dc8@...kaller.appspotmail.com

usb 1-1: USB disconnect, device number 2
==================================================================
BUG: KASAN: use-after-free in __media_entity_remove_links+0x134/0x160  
drivers/media/mc/mc-entity.c:779
Read of size 8 at addr ffff8881d199f120 by task kworker/1:2/1719

CPU: 1 PID: 1719 Comm: kworker/1:2 Not tainted 5.5.0-rc1-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+0x16/0x200 mm/kasan/report.c:374
  __kasan_report.cold+0x37/0x7f mm/kasan/report.c:506
  kasan_report+0xe/0x20 mm/kasan/common.c:639
  __media_entity_remove_links+0x134/0x160 drivers/media/mc/mc-entity.c:779
  __media_device_unregister_entity+0x187/0x300  
drivers/media/mc/mc-device.c:596
  media_device_unregister_entity+0x49/0x70 drivers/media/mc/mc-device.c:688
  v4l2_device_unregister_subdev+0x257/0x380  
drivers/media/v4l2-core/v4l2-device.c:283
  v4l2_device_unregister drivers/media/v4l2-core/v4l2-device.c:100 [inline]
  v4l2_device_unregister+0x139/0x220 drivers/media/v4l2-core/v4l2-device.c:88
  uvc_unregister_video+0x11a/0x210 drivers/media/usb/uvc/uvc_driver.c:1929
  uvc_disconnect+0xbc/0x160 drivers/media/usb/uvc/uvc_driver.c:2242
  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 22:
  save_stack+0x1b/0x80 mm/kasan/common.c:72
  set_track mm/kasan/common.c:80 [inline]
  __kasan_kmalloc mm/kasan/common.c:513 [inline]
  __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:486
  kmalloc include/linux/slab.h:556 [inline]
  kzalloc include/linux/slab.h:670 [inline]
  media_add_link+0x47/0x180 drivers/media/mc/mc-entity.c:592
  media_create_pad_link+0x1fb/0x530 drivers/media/mc/mc-entity.c:684
  uvc_mc_create_links drivers/media/usb/uvc/uvc_entity.c:50 [inline]
  uvc_mc_register_entities+0x468/0x77a drivers/media/usb/uvc/uvc_entity.c:114
  uvc_register_chains drivers/media/usb/uvc/uvc_driver.c:2075 [inline]
  uvc_probe.cold+0x2137/0x29de drivers/media/usb/uvc/uvc_driver.c:2201
  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 1719:
  save_stack+0x1b/0x80 mm/kasan/common.c:72
  set_track mm/kasan/common.c:80 [inline]
  kasan_set_free_info mm/kasan/common.c:335 [inline]
  __kasan_slab_free+0x129/0x170 mm/kasan/common.c:474
  slab_free_hook mm/slub.c:1425 [inline]
  slab_free_freelist_hook mm/slub.c:1458 [inline]
  slab_free mm/slub.c:3005 [inline]
  kfree+0xda/0x310 mm/slub.c:3957
  __media_entity_remove_link+0x25c/0x5d0 drivers/media/mc/mc-entity.c:622
  __media_entity_remove_links+0x86/0x160 drivers/media/mc/mc-entity.c:780
  __media_device_unregister_entity+0x187/0x300  
drivers/media/mc/mc-device.c:596
  media_device_unregister_entity+0x49/0x70 drivers/media/mc/mc-device.c:688
  v4l2_device_unregister_subdev+0x257/0x380  
drivers/media/v4l2-core/v4l2-device.c:283
  v4l2_device_unregister drivers/media/v4l2-core/v4l2-device.c:100 [inline]
  v4l2_device_unregister+0x139/0x220 drivers/media/v4l2-core/v4l2-device.c:88
  uvc_unregister_video+0x11a/0x210 drivers/media/usb/uvc/uvc_driver.c:1929
  uvc_disconnect+0xbc/0x160 drivers/media/usb/uvc/uvc_driver.c:2242
  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

The buggy address belongs to the object at ffff8881d199f100
  which belongs to the cache kmalloc-96 of size 96
The buggy address is located 32 bytes inside of
  96-byte region [ffff8881d199f100, ffff8881d199f160)
The buggy address belongs to the page:
page:ffffea00074667c0 refcount:1 mapcount:0 mapping:ffff8881da002f00  
index:0xffff8881d199fe80
raw: 0200000000000200 ffffea0007474e40 0000000e0000000e ffff8881da002f00
raw: ffff8881d199fe80 0000000080200016 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8881d199f000: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
  ffff8881d199f080: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
> ffff8881d199f100: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                                ^
  ffff8881d199f180: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
  ffff8881d199f200: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
==================================================================


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@...glegroups.com.

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