KASAN: use-after-free Read in v4l2_release (3)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: ae179410 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=132aa915e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=57adcee0a60380e2
dashboard link: https://syzkaller.appspot.com/bug?extid=75287f75e2fedd69d680
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+75287f...@syzkaller.appspotmail.com

usbvision_radio_close: Final disconnect
==================================================================
BUG: KASAN: use-after-free in v4l2_release+0x2f1/0x390
drivers/media/v4l2-core/v4l2-dev.c:459
Read of size 4 at addr ffff8881d13b5068 by task v4l_id/20136

CPU: 1 PID: 20136 Comm: v4l_id Not tainted 5.5.0-rc3-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+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
v4l2_release+0x2f1/0x390 drivers/media/v4l2-core/v4l2-dev.c:459
__fput+0x2d7/0x840 fs/file_table.c:280
task_work_run+0x13f/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x1d2/0x200 arch/x86/entry/common.c:164
prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
do_syscall_64+0x4e0/0x5c0 arch/x86/entry/common.c:304
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f70446a32b0
Code: 40 75 0b 31 c0 48 83 c4 08 e9 0c ff ff ff 48 8d 3d c5 32 08 00 e8 c0
07 02 00 83 3d 45 a3 2b 00 00 75 10 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff
ff 73 31 c3 48 83 ec 08 e8 ce 8a 01 00 48 89 04 24
RSP: 002b:00007ffee1722fd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007f70446a32b0
RDX: 0000000000000013 RSI: 0000000080685600 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000400884
R13: 00007ffee1723130 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 14633:
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]
usbvision_alloc drivers/media/usb/usbvision/usbvision-video.c:1315 [inline]
usbvision_probe.cold+0x5c5/0x1f21
drivers/media/usb/usbvision/usbvision-video.c:1469
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+0x141f/0x1bc0 drivers/base/core.c:2487
usb_set_configuration+0xe38/0x16c0 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+0x141f/0x1bc0 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
process_scheduled_works kernel/workqueue.c:2326 [inline]
worker_thread+0x7ab/0xe20 kernel/workqueue.c:2412
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 20136:
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
usbvision_release+0x181/0x1c0
drivers/media/usb/usbvision/usbvision-video.c:1364
usbvision_radio_close.cold+0x2b/0x74
drivers/media/usb/usbvision/usbvision-video.c:1130
v4l2_release+0x2e7/0x390 drivers/media/v4l2-core/v4l2-dev.c:455
__fput+0x2d7/0x840 fs/file_table.c:280
task_work_run+0x13f/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x1d2/0x200 arch/x86/entry/common.c:164
prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
do_syscall_64+0x4e0/0x5c0 arch/x86/entry/common.c:304
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8881d13b4000
which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 4200 bytes inside of
8192-byte region [ffff8881d13b4000, ffff8881d13b6000)
The buggy address belongs to the page:
page:ffffea000744ec00 refcount:1 mapcount:0 mapping:ffff8881da40c500
index:0x0 compound_mapcount: 0
raw: 0200000000010200 ffffea0007392a00 0000000300000003 ffff8881da40c500
raw: 0000000000000000 0000000000020002 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8881d13b4f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881d13b4f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8881d13b5000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8881d13b5080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881d13b5100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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 syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: 4cc301ee 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=17f5a721e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=9ba75825443d54bd

dashboard link: https://syzkaller.appspot.com/bug?extid=75287f75e2fedd69d680
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16a0b6f1e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1327dd76e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+75287f...@syzkaller.appspotmail.com

usbvision_set_audio: can't write iopin register for audio switching

usbvision_radio_close: Final disconnect
==================================================================
BUG: KASAN: use-after-free in v4l2_release+0x2f1/0x390 drivers/media/v4l2-core/v4l2-dev.c:459

Read of size 4 at addr ffff8881caba1068 by task v4l_id/1913

CPU: 1 PID: 1913 Comm: v4l_id Not tainted 5.5.0-rc6-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+0xef/0x16e lib/dump_stack.c:118

print_address_description.constprop.0.cold+0xd3/0x314 mm/kasan/report.c:374
__kasan_report.cold+0x37/0x85 mm/kasan/report.c:506

kasan_report+0xe/0x20 mm/kasan/common.c:639
v4l2_release+0x2f1/0x390 drivers/media/v4l2-core/v4l2-dev.c:459
__fput+0x2d7/0x840 fs/file_table.c:280
task_work_run+0x13f/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x1d2/0x200 arch/x86/entry/common.c:164
prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
syscall_return_slowpath arch/x86/entry/common.c:278 [inline]

do_syscall_64+0x4e0/0x5a0 arch/x86/entry/common.c:304
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fbeb0b822b0

Code: 40 75 0b 31 c0 48 83 c4 08 e9 0c ff ff ff 48 8d 3d c5 32 08 00 e8 c0 07 02 00 83 3d 45 a3 2b 00 00 75 10 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 ce 8a 01 00 48 89 04 24

RSP: 002b:00007ffe52d6b158 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007fbeb0b822b0

RDX: 0000000000000013 RSI: 0000000080685600 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000400884

R13: 00007ffe52d6b2b0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 94:

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]
usbvision_alloc drivers/media/usb/usbvision/usbvision-video.c:1315 [inline]
usbvision_probe.cold+0x5c5/0x1f21 drivers/media/usb/usbvision/usbvision-video.c:1469

usb_probe_interface+0x310/0x800 drivers/usb/core/driver.c:361
really_probe+0x290/0xad0 drivers/base/dd.c:548
driver_probe_device+0x223/0x350 drivers/base/dd.c:721
__device_attach_driver+0x1d1/0x290 drivers/base/dd.c:828
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
__device_attach+0x217/0x390 drivers/base/dd.c:894
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
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+0x290/0xad0 drivers/base/dd.c:548
driver_probe_device+0x223/0x350 drivers/base/dd.c:721
__device_attach_driver+0x1d1/0x290 drivers/base/dd.c:828
bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
__device_attach+0x217/0x390 drivers/base/dd.c:894
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
device_add+0x1459/0x1bf0 drivers/base/core.c:2487
usb_new_device.cold+0x540/0xcd0 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+0x21cb/0x4300 drivers/usb/core/hub.c:5552
process_one_work+0x945/0x15c0 kernel/workqueue.c:2264

process_scheduled_works kernel/workqueue.c:2326 [inline]
worker_thread+0x7ab/0xe20 kernel/workqueue.c:2412
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 1913:

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+0x117/0x160 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+0xd5/0x300 mm/slub.c:3957

usbvision_release+0x181/0x1c0 drivers/media/usb/usbvision/usbvision-video.c:1364
usbvision_radio_close.cold+0x2b/0x74 drivers/media/usb/usbvision/usbvision-video.c:1130
v4l2_release+0x2e7/0x390 drivers/media/v4l2-core/v4l2-dev.c:455
__fput+0x2d7/0x840 fs/file_table.c:280
task_work_run+0x13f/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x1d2/0x200 arch/x86/entry/common.c:164
prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
syscall_return_slowpath arch/x86/entry/common.c:278 [inline]

do_syscall_64+0x4e0/0x5a0 arch/x86/entry/common.c:304
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8881caba0000

which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 4200 bytes inside of

8192-byte region [ffff8881caba0000, ffff8881caba2000)

The buggy address belongs to the page:

page:ffffea00072ae800 refcount:1 mapcount:0 mapping:ffff8881da00c500 index:0x0 compound_mapcount: 0
raw: 0200000000010200 dead000000000100 dead000000000122 ffff8881da00c500
raw: 0000000000000000 0000000080020002 00000001ffffffff 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff8881caba0f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881caba0f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881caba1000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8881caba1080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881caba1100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

[Hillf Danton]

Wed, 22 Jan 2020 14:58:08 -0800 (PST)
> syzbot has found a reproducer for the following crash on:
>
> HEAD commit: 4cc301ee 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=17f5a721e00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=9ba75825443d54bd

> dashboard link: https://syzkaller.appspot.com/bug?extid=75287f75e2fedd69d680
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)

> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16a0b6f1e00000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1327dd76e00000
>

> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+75287f...@syzkaller.appspotmail.com
>

> usbvision_set_audio: can't write iopin register for audio switching

> usbvision_radio_close: Final disconnect
> ==================================================================
> BUG: KASAN: use-after-free in v4l2_release+0x2f1/0x390 drivers/media/v4l2-core/v4l2-dev.c:459

> Read of size 4 at addr ffff8881caba1068 by task v4l_id/1913
>

> CPU: 1 PID: 1913 Comm: v4l_id Not tainted 5.5.0-rc6-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+0xef/0x16e lib/dump_stack.c:118

> print_address_description.constprop.0.cold+0xd3/0x314 mm/kasan/report.c:374
> __kasan_report.cold+0x37/0x85 mm/kasan/report.c:506

> kasan_report+0xe/0x20 mm/kasan/common.c:639
> v4l2_release+0x2f1/0x390 drivers/media/v4l2-core/v4l2-dev.c:459
> __fput+0x2d7/0x840 fs/file_table.c:280
> task_work_run+0x13f/0x1c0 kernel/task_work.c:113
> tracehook_notify_resume include/linux/tracehook.h:188 [inline]
> exit_to_usermode_loop+0x1d2/0x200 arch/x86/entry/common.c:164
> prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
> syscall_return_slowpath arch/x86/entry/common.c:278 [inline]

> do_syscall_64+0x4e0/0x5a0 arch/x86/entry/common.c:304
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x7fbeb0b822b0

> Code: 40 75 0b 31 c0 48 83 c4 08 e9 0c ff ff ff 48 8d 3d c5 32 08 00 e8 c0 07 02 00 83 3d 45 a3 2b 00 00 75 10 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 ce 8a 01 00 48 89 04 24

> RSP: 002b:00007ffe52d6b158 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
> RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007fbeb0b822b0

> RDX: 0000000000000013 RSI: 0000000080685600 RDI: 0000000000000003
> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000400884

> R13: 00007ffe52d6b2b0 R14: 0000000000000000 R15: 0000000000000000
>
> Allocated by task 94:

> 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]
> usbvision_alloc drivers/media/usb/usbvision/usbvision-video.c:1315 [inline]
> usbvision_probe.cold+0x5c5/0x1f21 drivers/media/usb/usbvision/usbvision-video.c:1469

> usb_probe_interface+0x310/0x800 drivers/usb/core/driver.c:361
> really_probe+0x290/0xad0 drivers/base/dd.c:548
> driver_probe_device+0x223/0x350 drivers/base/dd.c:721

> __device_attach_driver+0x1d1/0x290 drivers/base/dd.c:828
> bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
> __device_attach+0x217/0x390 drivers/base/dd.c:894
> bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
> 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+0x290/0xad0 drivers/base/dd.c:548
> driver_probe_device+0x223/0x350 drivers/base/dd.c:721

> __device_attach_driver+0x1d1/0x290 drivers/base/dd.c:828
> bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
> __device_attach+0x217/0x390 drivers/base/dd.c:894
> bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
> device_add+0x1459/0x1bf0 drivers/base/core.c:2487
> usb_new_device.cold+0x540/0xcd0 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+0x21cb/0x4300 drivers/usb/core/hub.c:5552
> process_one_work+0x945/0x15c0 kernel/workqueue.c:2264

> process_scheduled_works kernel/workqueue.c:2326 [inline]
> worker_thread+0x7ab/0xe20 kernel/workqueue.c:2412
> kthread+0x318/0x420 kernel/kthread.c:255
> ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
>

> Freed by task 1913:

> 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+0x117/0x160 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+0xd5/0x300 mm/slub.c:3957

> usbvision_release+0x181/0x1c0 drivers/media/usb/usbvision/usbvision-video.c:1364
> usbvision_radio_close.cold+0x2b/0x74 drivers/media/usb/usbvision/usbvision-video.c:1130
> v4l2_release+0x2e7/0x390 drivers/media/v4l2-core/v4l2-dev.c:455
> __fput+0x2d7/0x840 fs/file_table.c:280
> task_work_run+0x13f/0x1c0 kernel/task_work.c:113
> tracehook_notify_resume include/linux/tracehook.h:188 [inline]
> exit_to_usermode_loop+0x1d2/0x200 arch/x86/entry/common.c:164
> prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
> syscall_return_slowpath arch/x86/entry/common.c:278 [inline]

> do_syscall_64+0x4e0/0x5a0 arch/x86/entry/common.c:304
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> The buggy address belongs to the object at ffff8881caba0000

> which belongs to the cache kmalloc-8k of size 8192
> The buggy address is located 4200 bytes inside of

> 8192-byte region [ffff8881caba0000, ffff8881caba2000)

> The buggy address belongs to the page:

> page:ffffea00072ae800 refcount:1 mapcount:0 mapping:ffff8881da00c500 index:0x0 compound_mapcount: 0
> raw: 0200000000010200 dead000000000100 dead000000000122 ffff8881da00c500

> raw: 0000000000000000 0000000080020002 00000001ffffffff 0000000000000000

> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:

> ffff8881caba0f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8881caba0f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >ffff8881caba1000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ^
> ffff8881caba1080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8881caba1100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================


Add the release callback for usbvision video device and use it to release
resources when the last reference to the device goes away.

--- a/drivers/media/usb/usbvision/usbvision-video.c
+++ b/drivers/media/usb/usbvision/usbvision-video.c
@@ -401,7 +401,6 @@ static int usbvision_v4l2_close(struct f

if (r) {
printk(KERN_INFO "%s: Final disconnect\n", __func__);
- usbvision_release(usbvision);
return 0;
}

@@ -409,6 +408,11 @@ static int usbvision_v4l2_close(struct f
return v4l2_fh_release(file);
}

+static void usbvision_video_device_release(struct video_device *vdev)
+{
+ struct usb_usbvision *usbvision = video_get_drvdata(vdev);
+ usbvision_release(usbvision);
+}

/*
* usbvision_ioctl()
@@ -1181,7 +1185,7 @@ static struct video_device usbvision_vid
.fops = &usbvision_fops,
.ioctl_ops = &usbvision_ioctl_ops,
.name = "usbvision-video",
- .release = video_device_release_empty,
+ .release = usbvision_video_device_release,
.tvnorms = USBVISION_NORMS,
};

--- a/drivers/media/v4l2-core/v4l2-dev.c
+++ b/drivers/media/v4l2-core/v4l2-dev.c
@@ -206,7 +206,10 @@ static void v4l2_device_release(struct d
}
#endif

- /* Do not call v4l2_device_put if there is no release callback set.
+ /*
+ * Decrease v4l2_device refcount
+ *
+ * Do not call v4l2_device_put if there is no release callback set.
* Drivers that have no v4l2_device release callback might free the
* v4l2_dev instance in the video_device release callback below, so we
* must perform this check here.
@@ -214,16 +217,12 @@ static void v4l2_device_release(struct d
* TODO: In the long run all drivers that use v4l2_device should use the
* v4l2_device release callback. This check will then be unnecessary.
*/
- if (v4l2_dev->release == NULL)
- v4l2_dev = NULL;
+ if (v4l2_dev->release)
+ v4l2_device_put(v4l2_dev);

/* Release video_device and perform other
cleanups as needed. */
vdev->release(vdev);
-
- /* Decrease v4l2_device refcount */
- if (v4l2_dev)
- v4l2_device_put(v4l2_dev);
}

static struct class video_class = {
--

[Laurent Pinchart]

Hi Hillf,

Would you be able to submit this with a commit message and your
Signed-off-by line ?

Regards,

Laurent Pinchart

[Hillf Danton]

On Thu, 23 Jan 2020 14:19:47 +0200 Laurent Pinchart wrote:
> On Thu, Jan 23, 2020 at 06:27:07PM +0800, Hillf Danton wrote:

> > Wed, 22 Jan 2020 14:58:08 -0800 (PST)
> > > syzbot has found a reproducer for the following crash on:
> > >
> > > HEAD commit: 4cc301ee 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=17f5a721e00000
> > > kernel config: https://syzkaller.appspot.com/x/.config?x=9ba75825443d54bd
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=75287f75e2fedd69d680
> > > compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16a0b6f1e00000
> > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1327dd76e00000
> > >
> > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > Reported-by: syzbot+75287f...@syzkaller.appspotmail.com
> > >
> > > usbvision_set_audio: can't write iopin register for audio switching
> > > usbvision_radio_close: Final disconnect
> > > ==================================================================
> > > BUG: KASAN: use-after-free in v4l2_release+0x2f1/0x390 drivers/media/v4l2-core/v4l2-dev.c:459
> > > Read of size 4 at addr ffff8881caba1068 by task v4l_id/1913

<snip>

> > Add the release callback for usbvision video device and use it to release
> > resources when the last reference to the device goes away.
>

> Would you be able to submit this with a commit message and your
> Signed-off-by line ?

---8<---
Subject: [PATCH] media: usbvision: add the release callback for video device
From: Hillf Danton <hda...@sina.com>

To fix the UAF syzbot reported,

BUG: KASAN: use-after-free in v4l2_release+0x2f1/0x390 drivers/media/v4l2-core/v4l2-dev.c:459

a release cb which is a simple wrapper of usbvision_release() is added
for releasing resources as the last reference to the usbvision video
device goes away.

Reported-by: syzbot <syzbot+75287f...@syzkaller.appspotmail.com>
Fixes: 2aa689dd8057 ("[media] usbvision: embed video_device")
Cc: Hans Verkuil <hans.v...@cisco.com>
Signed-off-by: Hillf Danton <hda...@sina.com>
---

[Andrey Konovalov]

#syz test: https://github.com/google/kasan.git ae179410

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer still triggered crash:
WARNING in kernfs_remove_by_name_ns

------------[ cut here ]------------
kernfs: can not remove 'version', no directory
WARNING: CPU: 1 PID: 94 at fs/kernfs/dir.c:1507 kernfs_remove_by_name_ns+0x98/0xb0 fs/kernfs/dir.c:1507
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 94 Comm: kworker/1:2 Not tainted 5.5.0-rc3-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

panic+0x2aa/0x6e1 kernel/panic.c:221
__warn.cold+0x2f/0x30 kernel/panic.c:582
report_bug+0x27b/0x2f0 lib/bug.c:195
fixup_bug arch/x86/kernel/traps.c:174 [inline]
fixup_bug arch/x86/kernel/traps.c:169 [inline]
do_error_trap+0x12b/0x1e0 arch/x86/kernel/traps.c:267
do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286
invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:kernfs_remove_by_name_ns+0x98/0xb0 fs/kernfs/dir.c:1507
Code: b1 ff 48 c7 c7 20 13 1d 87 41 bc fe ff ff ff e8 2e fe fe 03 eb d9 e8 47 4d b1 ff 4c 89 e6 48 c7 c7 c0 51 f1 85 e8 20 33 86 ff <0f> 0b 41 bc fe ff ff ff eb bb 0f 1f 40 00 66 2e 0f 1f 84 00 00 00
RSP: 0018:ffff8881d5d47708 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff8881cba58390 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff812959ad RDI: ffffed103aba8ed3
RBP: 0000000000000000 R08: ffff8881d6d2c980 R09: fffffbfff1269aae
R10: fffffbfff1269aad R11: ffffffff8934d56f R12: ffffffff8671eb40
R13: 0000000000000000 R14: 0000000000000000 R15: 000000000000000c
sysfs_remove_file include/linux/sysfs.h:536 [inline]
device_remove_file+0x25/0x30 drivers/base/core.c:1869
usbvision_remove_sysfs drivers/media/usb/usbvision/usbvision-video.c:287 [inline]
usbvision_release+0x88/0x1c0 drivers/media/usb/usbvision/usbvision-video.c:1360
v4l2_device_release+0x29a/0x3e0 drivers/media/v4l2-core/v4l2-dev.c:225
device_release+0x71/0x200 drivers/base/core.c:1358
kobject_cleanup lib/kobject.c:693 [inline]
kobject_release lib/kobject.c:722 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x256/0x550 lib/kobject.c:739
put_device drivers/base/core.c:2586 [inline]
device_unregister+0x34/0xc0 drivers/base/core.c:2697
video_unregister_device+0xa2/0xc0 drivers/media/v4l2-core/v4l2-dev.c:1075
usbvision_unregister_video drivers/media/usb/usbvision/usbvision-video.c:1255 [inline]
usbvision_unregister_video+0xfb/0x120 drivers/media/usb/usbvision/usbvision-video.c:1242
usbvision_release+0x10d/0x1c0 drivers/media/usb/usbvision/usbvision-video.c:1361
usbvision_disconnect+0x171/0x1e0 drivers/media/usb/usbvision/usbvision-video.c:1593
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+0x2eb/0x5a0 drivers/base/bus.c:532
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: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+0x1a1d/0x4300 drivers/usb/core/hub.c:5552
process_one_work+0x945/0x15c0 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

Kernel Offset: disabled
Rebooting in 86400 seconds..


Tested on:

commit: ae179410 usb: gadget: add raw-gadget interface
git tree: https://github.com/google/kasan.git
console output: https://syzkaller.appspot.com/x/log.txt?x=133b3611e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=ad1d751a3a72ae57

dashboard link: https://syzkaller.appspot.com/bug?extid=75287f75e2fedd69d680
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

patch: https://syzkaller.appspot.com/x/patch.diff?x=15921b69e00000

[Dan Carpenter]

This would work but another approach would be to to allocate "usbvision"
with devm_kzalloc(&dev->dev,... I believe that would postpone the free
enough to solve the use after free but I hadn't tested it yet. But
other drivers do that so hopefully it works.

regards,
dan carpenter

[Dan Carpenter]

Syzbot triggered a use after free in v5.5-rc6:

BUG: KASAN: use-after-free in v4l2_release+0x2f1/0x390 drivers/media/v4l2-core/v4l2-dev.c:459

Allocated by task 94:

usbvision_alloc drivers/media/usb/usbvision/usbvision-video.c:1315 [inline]
usbvision_probe.cold+0x5c5/0x1f21 drivers/media/usb/usbvision/usbvision-video.c:1469

Freed by task 1913:

kfree+0xd5/0x300 mm/slub.c:3957
usbvision_release+0x181/0x1c0 drivers/media/usb/usbvision/usbvision-video.c:1364
usbvision_radio_close.cold+0x2b/0x74 drivers/media/usb/usbvision/usbvision-video.c:1130
v4l2_release+0x2e7/0x390 drivers/media/v4l2-core/v4l2-dev.c:455

The problem is that the v4l2_release() calls usbvision_release() which
frees "usbvision" but v4l2_release() still wants to use
"usbvision->vdev". One solution is to make this devm_ allocated memory
so the memory isn't freed until later.

Reported-by: syzbot+75287f...@syzkaller.appspotmail.com
Signed-off-by: Dan Carpenter <dan.ca...@oracle.com>
---
I copied this idea from a different driver, but I haven't tested it.
I wanted to try the #syz fix command to see if it works.

drivers/media/usb/usbvision/usbvision-video.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/media/usb/usbvision/usbvision-video.c b/drivers/media/usb/usbvision/usbvision-video.c
index 93d36aab824f..07b4763062c4 100644
--- a/drivers/media/usb/usbvision/usbvision-video.c
+++ b/drivers/media/usb/usbvision/usbvision-video.c
@@ -1312,7 +1312,7 @@ static struct usb_usbvision *usbvision_alloc(struct usb_device *dev,
{
struct usb_usbvision *usbvision;

- usbvision = kzalloc(sizeof(*usbvision), GFP_KERNEL);
+ usbvision = devm_kzalloc(&dev->dev, sizeof(*usbvision), GFP_KERNEL);
if (!usbvision)
return NULL;

@@ -1336,7 +1336,6 @@ static struct usb_usbvision *usbvision_alloc(struct usb_device *dev,
v4l2_ctrl_handler_free(&usbvision->hdl);
v4l2_device_unregister(&usbvision->v4l2_dev);
err_free:
- kfree(usbvision);
return NULL;
}

@@ -1361,7 +1360,6 @@ static void usbvision_release(struct usb_usbvision *usbvision)

v4l2_ctrl_handler_free(&usbvision->hdl);
v4l2_device_unregister(&usbvision->v4l2_dev);
- kfree(usbvision);

PDEBUG(DBG_PROBE, "success");
}
--
2.11.0

[Hillf Danton]

Fri, 24 Jan 2020 04:54:03 -0800

> commit: ae179410 usb: gadget: add raw-gadget interface
> git tree: https://github.com/google/kasan.git

> console output: https://syzkaller.appspot.com/x/log.txt?x=133b3611e00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=ad1d751a3a72ae57

> dashboard link: https://syzkaller.appspot.com/bug?extid=75287f75e2fedd69d680
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)

> patch: https://syzkaller.appspot.com/x/patch.diff?x=15921b69e00000

Add reentrance check in usbvision_release() for releasing resources only
once.

--- a/drivers/media/usb/usbvision/usbvision-video.c
+++ b/drivers/media/usb/usbvision/usbvision-video.c
@@ -1351,6 +1351,8 @@ static void usbvision_release(struct usb
{
PDEBUG(DBG_PROBE, "");

+ if (usbvision->initialized == 0)
+ return;
usbvision->initialized = 0;

usbvision_remove_sysfs(&usbvision->vdev);
--

[Hans Verkuil]

On 1/24/20 3:13 PM, Dan Carpenter wrote:
> Syzbot triggered a use after free in v5.5-rc6:
>
> BUG: KASAN: use-after-free in v4l2_release+0x2f1/0x390 drivers/media/v4l2-core/v4l2-dev.c:459
>
> Allocated by task 94:
> usbvision_alloc drivers/media/usb/usbvision/usbvision-video.c:1315 [inline]
> usbvision_probe.cold+0x5c5/0x1f21 drivers/media/usb/usbvision/usbvision-video.c:1469
>
> Freed by task 1913:
> kfree+0xd5/0x300 mm/slub.c:3957
> usbvision_release+0x181/0x1c0 drivers/media/usb/usbvision/usbvision-video.c:1364
> usbvision_radio_close.cold+0x2b/0x74 drivers/media/usb/usbvision/usbvision-video.c:1130
> v4l2_release+0x2e7/0x390 drivers/media/v4l2-core/v4l2-dev.c:455
>
> The problem is that the v4l2_release() calls usbvision_release() which
> frees "usbvision" but v4l2_release() still wants to use
> "usbvision->vdev". One solution is to make this devm_ allocated memory
> so the memory isn't freed until later.

devm_ allocated memory is freed after disconnect, so I doubt this will help, or at
best it will just move the problem elsewhere.

The right approach would be to use the release() callback from struct v4l2_device:
that's called when the very last open filehandle is closed.

But I'm not sure if it is worth the effort. The usbvision driver is a mess and
personally I think it should be deprecated.

Regards,

Hans

[Laurent Pinchart]

Hi Hans,

On Fri, Feb 14, 2020 at 11:06:36AM +0100, Hans Verkuil wrote:
> On 1/24/20 3:13 PM, Dan Carpenter wrote:
> > Syzbot triggered a use after free in v5.5-rc6:
> >
> > BUG: KASAN: use-after-free in v4l2_release+0x2f1/0x390 drivers/media/v4l2-core/v4l2-dev.c:459
> >
> > Allocated by task 94:
> > usbvision_alloc drivers/media/usb/usbvision/usbvision-video.c:1315 [inline]
> > usbvision_probe.cold+0x5c5/0x1f21 drivers/media/usb/usbvision/usbvision-video.c:1469
> >
> > Freed by task 1913:
> > kfree+0xd5/0x300 mm/slub.c:3957
> > usbvision_release+0x181/0x1c0 drivers/media/usb/usbvision/usbvision-video.c:1364
> > usbvision_radio_close.cold+0x2b/0x74 drivers/media/usb/usbvision/usbvision-video.c:1130
> > v4l2_release+0x2e7/0x390 drivers/media/v4l2-core/v4l2-dev.c:455
> >
> > The problem is that the v4l2_release() calls usbvision_release() which
> > frees "usbvision" but v4l2_release() still wants to use
> > "usbvision->vdev". One solution is to make this devm_ allocated memory
> > so the memory isn't freed until later.
>
> devm_ allocated memory is freed after disconnect, so I doubt this will help, or at
> best it will just move the problem elsewhere.

Yes, devm_*alloc is evil :-( It has spread to many drivers and is used
incorrectly in most cases.

> The right approach would be to use the release() callback from struct v4l2_device:
> that's called when the very last open filehandle is closed.

Hillf Danton has sent a patch to do so in the "Re: KASAN: use-after-free
Read in v4l2_release (3)" thread. Have you seen it ?

> But I'm not sure if it is worth the effort. The usbvision driver is a mess and
> personally I think it should be deprecated.

I agree.

--
Regards,

Laurent Pinchart

[Hans Verkuil]

Ah, that was never mailed to linux-media, so never ended up in patchwork. And
if it ain't in patchwork, then I don't know about it :-)

Hillf, if you want your patch to be merged, then make sure it is CC-ed to
linux-media as well.

Regards,

Hans

[Hillf Danton]

On Fri, 14 Feb 2020 12:30:29 +0100 Hans Verkuil wrote:
>
> Hillf, if you want your patch to be merged, then make sure it is CC-ed to
> linux-media as well.

Please pick it up if it makes a sense to you and it was sent with
linux-media added on the Cc list as it is known for a while that
my mail agent is rejected @vger.kernel.org for what I am not clear
about. It makes my day occasionally :P

Thanks
Hillf

[Hans Verkuil]

I don't I ever received the full patch, only replies to your patch.

Please mail your patch directly to me so I have a clean version.

Regards,

Hans

>
> Thanks
> Hillf
>

[Hillf Danton]

On Fri, 14 Feb 2020 13:21:03 +0100 Hans Verkuil wrote:
> On 2/14/20 1:14 PM, Hillf Danton wrote:
> >

> I don't I ever received the full patch, only replies to your patch.
>

=========
Please take a look at the Cc tag in the snippet from
https://lore.kernel.org/lkml/b1d071e2-0428-a08c...@xs4all.nl/T/#m13f2c16b7cd1892f6a0b58b72ce37979cb6940b9

> Subject: [PATCH] media: usbvision: add the release callback for video device
> From: Hillf Danton <hda...@sina.com>
>
> To fix the UAF syzbot reported,
>

> BUG: KASAN: use-after-free in v4l2_release+0x2f1/0x390 drivers/media/v4l2-core/v4l2-dev.c:459
>

> a release cb which is a simple wrapper of usbvision_release() is added
> for releasing resources as the last reference to the usbvision video
> device goes away.
>
> Reported-by: syzbot <syzbot+75287f...@syzkaller.appspotmail.com>
> Fixes: 2aa689dd8057 ("[media] usbvision: embed video_device")
> Cc: Hans Verkuil <hans.v...@cisco.com>
> Signed-off-by: Hillf Danton <hda...@sina.com>
> ---

=========

[Hillf Danton]

On Fri, 14 Feb 2020 14:34:49 +0100 Hans Verkuil wrote:
>
> So please mail me a properly formatted patch so I can forward it to linux-media
> for you.


---8<---

Subject: [PATCH] media: usbvision: add the release callback for video device
From: Hillf Danton <hda...@sina.com>

To fix the UAF like

BUG: KASAN: use-after-free in v4l2_release+0x2f1/0x390 drivers/media/v4l2-core/v4l2-dev.c:459

Read of size 4 at addr ffff8881caba1068 by task v4l_id/1913

a callback which is a simple wrapper of usbvision_release() is added

for releasing resources as the last reference to the usbvision video

device goes home.

Reported-by: syzbot <syzbot+75287f...@syzkaller.appspotmail.com>
Fixes: 2aa689dd8057 ("[media] usbvision: embed video_device")

Cc: Hans Verkuil <hver...@xs4all.nl>

Signed-off-by: Hillf Danton <hda...@sina.com>
---

--- a/drivers/media/usb/usbvision/usbvision-video.c
+++ b/drivers/media/usb/usbvision/usbvision-video.c

[Hans Verkuil]

Ah, my work email. And I always delete posts mailed to that if it is also CC-ed
to linux-media. Which didn't actually arrive there in your case. And it's no longer
in my trash folder either.

So please mail me a properly formatted patch so I can forward it to linux-media
for you.

Regards,

Hans

[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.