KASAN: use-after-free Read in __media_entity_remove

KASAN: use-after-free Read in __media_entity_remove_links
Status: upstream: reported C repro on 2019/12/16 13:15
Reported-by: syzbot+0b0095300dfeb8a83dc8@syzkaller.appspotmail.com
First crash: 442d, last: 343d

Sample crash report:

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 ffff8881ce1c2320 by task kworker/1:0/17

CPU: 1 PID: 17 Comm: kworker/1:0 Not tainted 5.6.0-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.cold+0xd3/0x314 mm/kasan/report.c:374
 __kasan_report.cold+0x37/0x77 mm/kasan/report.c:506
 kasan_report+0xe/0x20 mm/kasan/common.c:641
 __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:1957
 uvc_disconnect+0xbc/0x160 drivers/media/usb/uvc/uvc_driver.c:2270
 usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
 __device_release_driver drivers/base/dd.c:1137 [inline]
 device_release_driver_internal+0x42f/0x500 drivers/base/dd.c:1168
 bus_remove_device+0x2eb/0x5a0 drivers/base/bus.c:533
 device_del+0x481/0xd30 drivers/base/core.c:2664
 usb_disable_device+0x23d/0x790 drivers/usb/core/message.c:1237
 usb_disconnect+0x293/0x900 drivers/usb/core/hub.c:2201
 hub_port_connect drivers/usb/core/hub.c:5036 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5325 [inline]
 port_event drivers/usb/core/hub.c:5471 [inline]
 hub_event+0x1a1d/0x4300 drivers/usb/core/hub.c:5553
 process_one_work+0x94b/0x1620 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 95:
 save_stack+0x1b/0x80 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc mm/kasan/common.c:515 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:488
 kmalloc include/linux/slab.h:555 [inline]
 kzalloc include/linux/slab.h:669 [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:2103 [inline]
 uvc_probe.cold+0x205c/0x2a51 drivers/media/usb/uvc/uvc_driver.c:2229
 usb_probe_interface+0x310/0x800 drivers/usb/core/driver.c:361
 really_probe+0x290/0xac0 drivers/base/dd.c:551
 driver_probe_device+0x223/0x350 drivers/base/dd.c:724
 __device_attach_driver+0x1d1/0x290 drivers/base/dd.c:831
 bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:431
 __device_attach+0x217/0x390 drivers/base/dd.c:897
 bus_probe_device+0x1e4/0x290 drivers/base/bus.c:491
 device_add+0x1459/0x1bf0 drivers/base/core.c:2487
 usb_set_configuration+0xe47/0x17d0 drivers/usb/core/message.c:2023
 generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
 usb_probe_device+0xaf/0x140 drivers/usb/core/driver.c:266
 really_probe+0x290/0xac0 drivers/base/dd.c:551
 driver_probe_device+0x223/0x350 drivers/base/dd.c:724
 __device_attach_driver+0x1d1/0x290 drivers/base/dd.c:831
 bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:431
 __device_attach+0x217/0x390 drivers/base/dd.c:897
 bus_probe_device+0x1e4/0x290 drivers/base/bus.c:491
 device_add+0x1459/0x1bf0 drivers/base/core.c:2487
 usb_new_device.cold+0x540/0xcd0 drivers/usb/core/hub.c:2538
 hub_port_connect drivers/usb/core/hub.c:5185 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5325 [inline]
 port_event drivers/usb/core/hub.c:5471 [inline]
 hub_event+0x21cb/0x4300 drivers/usb/core/hub.c:5553
 process_one_work+0x94b/0x1620 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 17:
 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:337 [inline]
 __kasan_slab_free+0x117/0x160 mm/kasan/common.c:476
 slab_free_hook mm/slub.c:1444 [inline]
 slab_free_freelist_hook mm/slub.c:1477 [inline]
 slab_free mm/slub.c:3024 [inline]
 kfree+0xd5/0x300 mm/slub.c:3976
 __media_entity_remove_link+0x28c/0x660 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:1957
 uvc_disconnect+0xbc/0x160 drivers/media/usb/uvc/uvc_driver.c:2270
 usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
 __device_release_driver drivers/base/dd.c:1137 [inline]
 device_release_driver_internal+0x42f/0x500 drivers/base/dd.c:1168
 bus_remove_device+0x2eb/0x5a0 drivers/base/bus.c:533
 device_del+0x481/0xd30 drivers/base/core.c:2664
 usb_disable_device+0x23d/0x790 drivers/usb/core/message.c:1237
 usb_disconnect+0x293/0x900 drivers/usb/core/hub.c:2201
 hub_port_connect drivers/usb/core/hub.c:5036 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5325 [inline]
 port_event drivers/usb/core/hub.c:5471 [inline]
 hub_event+0x1a1d/0x4300 drivers/usb/core/hub.c:5553
 process_one_work+0x94b/0x1620 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 ffff8881ce1c2300
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 32 bytes inside of
 96-byte region [ffff8881ce1c2300, ffff8881ce1c2360)
The buggy address belongs to the page:
page:ffffea0007387080 refcount:1 mapcount:0 mapping:ffff8881da002f00 index:0x0
flags: 0x200000000000200(slab)
raw: 0200000000000200 ffffea0007397c00 0000000200000002 ffff8881da002f00
raw: 0000000000000000 0000000080200020 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881ce1c2200: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc
 ffff8881ce1c2280: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc
>ffff8881ce1c2300: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                               ^
 ffff8881ce1c2380: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff8881ce1c2400: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
==================================================================

Crashes (7):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro
ci2-upstream-usb	2020/02/15 16:17	https://github.com/google/kasan.git usb-fuzzer	7f0cd6c7	5d7b90f1	.config	log	report	syz	C
ci2-upstream-usb	2019/12/20 06:56	https://github.com/google/kasan.git usb-fuzzer	ecdf2214	36650b4b	.config	log	report	syz	C
ci2-upstream-usb	2019/12/16 00:37	https://github.com/google/kasan.git usb-fuzzer	4cc037ec	eef6e580	.config	log	report	syz	C
ci2-upstream-usb	2020/03/23 14:41	https://github.com/google/kasan.git usb-fuzzer	e17994d1	78267cec	.config	log	report
ci2-upstream-usb	2020/01/16 14:21	https://github.com/google/kasan.git usb-fuzzer	4cc301ee	3de7aabb	.config	log	report
ci2-upstream-usb	2020/01/09 19:18	https://github.com/google/kasan.git usb-fuzzer	ae179410	4de4e9f0	.config	log	report
ci2-upstream-usb	2019/12/16 00:23	https://github.com/google/kasan.git usb-fuzzer	4cc037ec	eef6e580	.config	log	report