KASAN: use-after-free Read in uvc_probe

[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=132223fee00000
kernel config: https://syzkaller.appspot.com/x/.config?x=ad1d751a3a72ae57
dashboard link: https://syzkaller.appspot.com/bug?extid=9a48339b077c5a80b869
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16857325e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=142e069ee00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+9a4833...@syzkaller.appspotmail.com

usb 1-1: New USB device found, idVendor=0bd3, idProduct=0555,
bcdDevice=69.6a
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
usb 1-1: string descriptor 0 read error: -71
uvcvideo: Found UVC 0.00 device <unnamed> (0bd3:0555)
==================================================================
BUG: KASAN: use-after-free in uvc_register_terms
drivers/media/usb/uvc/uvc_driver.c:2038 [inline]
BUG: KASAN: use-after-free in uvc_register_chains
drivers/media/usb/uvc/uvc_driver.c:2070 [inline]
BUG: KASAN: use-after-free in uvc_probe.cold+0x2193/0x29de
drivers/media/usb/uvc/uvc_driver.c:2201
Read of size 2 at addr ffff8881d4f1bc2e by task kworker/1:2/94

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
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
uvc_register_terms drivers/media/usb/uvc/uvc_driver.c:2038 [inline]
uvc_register_chains drivers/media/usb/uvc/uvc_driver.c:2070 [inline]
uvc_probe.cold+0x2193/0x29de drivers/media/usb/uvc/uvc_driver.c:2201
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
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 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]
uvc_alloc_chain+0x48/0xfa drivers/media/usb/uvc/uvc_driver.c:1692
uvc_scan_device drivers/media/usb/uvc/uvc_driver.c:1818 [inline]
uvc_probe.cold+0x15f0/0x29de drivers/media/usb/uvc/uvc_driver.c:2197
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
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 94:
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
uvc_scan_device drivers/media/usb/uvc/uvc_driver.c:1825 [inline]
uvc_probe.cold+0x16fd/0x29de drivers/media/usb/uvc/uvc_driver.c:2197
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
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 ffff8881d4f1bc00
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 46 bytes inside of
256-byte region [ffff8881d4f1bc00, ffff8881d4f1bd00)
The buggy address belongs to the page:
page:ffffea000753c680 refcount:1 mapcount:0 mapping:ffff8881da002780
index:0x0 compound_mapcount: 0
raw: 0200000000010200 ffffea000753c600 0000000300000003 ffff8881da002780
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8881d4f1bb00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8881d4f1bb80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff8881d4f1bc00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8881d4f1bc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881d4f1bd00: fc fc fc fc fc fc fc fc fc fc fc fc 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 syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

[Oliver Neukum]

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

From db844641a5e30f3cfc0ce9cde156b3cc356b6c0c Mon Sep 17 00:00:00 2001
From: Oliver Neukum <one...@suse.com>
Date: Mon, 10 Feb 2020 15:10:36 +0100
Subject: [PATCH] UVC: deal with unnamed streams

The pointer can be NULL

Signed-off-by: Oliver Neukum <one...@suse.com>
---
drivers/media/usb/uvc/uvc_driver.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 99883550375e..26558a89f2fe 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -2069,7 +2069,8 @@ static int uvc_register_terms(struct uvc_device *dev,
stream = uvc_stream_by_id(dev, term->id);
if (stream == NULL) {
uvc_printk(KERN_INFO, "No streaming interface found "
- "for terminal %u.", term->id);
+ "for terminal %u.",
+ term->id ? term->id : "(Unnamed)");
continue;
}

--
2.16.4

[Laurent Pinchart]

Hi Oliver,

Thank you for the patch.

Have you tried compiling this ?

> continue;
> }
>

--
Regards,

Laurent Pinchart

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer still triggered crash:
KASAN: use-after-free Read in uvc_probe

usb 2-1: string descriptor 0 read error: -71

uvcvideo: Found UVC 0.00 device <unnamed> (0bd3:0555)
==================================================================
BUG: KASAN: use-after-free in uvc_register_terms drivers/media/usb/uvc/uvc_driver.c:2038 [inline]

BUG: KASAN: use-after-free in uvc_register_chains drivers/media/usb/uvc/uvc_driver.c:2071 [inline]
BUG: KASAN: use-after-free in uvc_probe.cold+0x2193/0x29fe drivers/media/usb/uvc/uvc_driver.c:2202
Read of size 2 at addr ffff8881d933182e by task kworker/0:2/95

CPU: 0 PID: 95 Comm: kworker/0:2 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
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
uvc_register_terms drivers/media/usb/uvc/uvc_driver.c:2038 [inline]

uvc_register_chains drivers/media/usb/uvc/uvc_driver.c:2071 [inline]
uvc_probe.cold+0x2193/0x29fe drivers/media/usb/uvc/uvc_driver.c:2202

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: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]
uvc_alloc_chain+0x48/0xfa drivers/media/usb/uvc/uvc_driver.c:1692
uvc_scan_device drivers/media/usb/uvc/uvc_driver.c:1818 [inline]

uvc_probe.cold+0x15f0/0x29fe drivers/media/usb/uvc/uvc_driver.c:2198

Freed by task 95:

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
uvc_scan_device drivers/media/usb/uvc/uvc_driver.c:1825 [inline]

uvc_probe.cold+0x16fd/0x29fe drivers/media/usb/uvc/uvc_driver.c:2198

The buggy address belongs to the object at ffff8881d9331800

which belongs to the cache kmalloc-256 of size 256
The buggy address is located 46 bytes inside of

256-byte region [ffff8881d9331800, ffff8881d9331900)

The buggy address belongs to the page:

page:ffffea000764cc00 refcount:1 mapcount:0 mapping:ffff8881da002780 index:0x0 compound_mapcount: 0
raw: 0200000000010200 ffffea0007648d80 0000000e0000000e ffff8881da002780

raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff8881d9331700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8881d9331780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881d9331800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8881d9331880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881d9331900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


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=13d466e9e00000

kernel config: https://syzkaller.appspot.com/x/.config?x=ad1d751a3a72ae57
dashboard link: https://syzkaller.appspot.com/bug?extid=9a48339b077c5a80b869
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

patch: https://syzkaller.appspot.com/x/patch.diff?x=16022395e00000

[Oliver Neukum]

Yes. It does compile. Why?

Regards
Oliver

[Laurent Pinchart]

Hi Oliver,

Because term->id is a u8, "(Unnamed)" is a const char *, and %u requires
an integer. I'm surprised the compiler doesn't complain, but in any
case, it's not right :-)

--
Regards,

Laurent Pinchart

[Oliver Neukum]

Oi, damnation, you are right. For some reason I saw a %s there.

Sorry
Oliver

[Andrey Konovalov]

Fixed by something.

#syz invalid