KASAN: use-after-free Read in cpia2_usb_disconnect

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 9a33b369 usb-fuzzer: main usb gadget fuzzer driver
git tree: https://github.com/google/kasan/tree/usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=1463a267200000
kernel config: https://syzkaller.appspot.com/x/.config?x=23e37f59d94ddd15
dashboard link: https://syzkaller.appspot.com/bug?extid=0c90fc937c84f97d0aa6
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13af9c23200000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+0c90fc...@syzkaller.appspotmail.com

cpia2: Control message failed, err val = -19
cpia2: Message: request = 0x1, start = 0xA9
cpia2: Message: count = 1, register[0] = 0x0
cpia2: Unexpected error: -19
==================================================================
BUG: KASAN: use-after-free in cpia2_usb_disconnect+0x1a9/0x1c0
drivers/media/usb/cpia2/cpia2_usb.c:907
Read of size 8 at addr ffff8880a09f0a58 by task kworker/0:1/12

CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.1.0-rc4-319354-g9a33b36 #3
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+0xe8/0x16e lib/dump_stack.c:113
print_address_description+0x6c/0x236 mm/kasan/report.c:187
kasan_report.cold+0x1a/0x3c mm/kasan/report.c:317
cpia2_usb_disconnect+0x1a9/0x1c0 drivers/media/usb/cpia2/cpia2_usb.c:907
usb_unbind_interface+0x1c9/0x980 drivers/usb/core/driver.c:423
__device_release_driver drivers/base/dd.c:1082 [inline]
device_release_driver_internal+0x436/0x4f0 drivers/base/dd.c:1113
bus_remove_device+0x302/0x5c0 drivers/base/bus.c:556
device_del+0x467/0xb90 drivers/base/core.c:2269
usb_disable_device+0x242/0x790 drivers/usb/core/message.c:1235
usb_disconnect+0x298/0x870 drivers/usb/core/hub.c:2197
hub_port_connect drivers/usb/core/hub.c:4940 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
port_event drivers/usb/core/hub.c:5350 [inline]
hub_event+0xcd2/0x3b00 drivers/usb/core/hub.c:5432
process_one_work+0x90f/0x1580 kernel/workqueue.c:2269
process_scheduled_works kernel/workqueue.c:2331 [inline]
worker_thread+0x7b0/0xe20 kernel/workqueue.c:2417
kthread+0x313/0x420 kernel/kthread.c:253
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Allocated by task 12:
set_track mm/kasan/common.c:87 [inline]
__kasan_kmalloc mm/kasan/common.c:497 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:470
kmalloc include/linux/slab.h:547 [inline]
kzalloc include/linux/slab.h:742 [inline]
cpia2_init_camera_struct+0x45/0x110
drivers/media/usb/cpia2/cpia2_core.c:2185
cpia2_usb_probe.cold+0x37/0x45a drivers/media/usb/cpia2/cpia2_usb.c:842
usb_probe_interface+0x31d/0x820 drivers/usb/core/driver.c:361
really_probe+0x2da/0xb10 drivers/base/dd.c:509
driver_probe_device+0x21d/0x350 drivers/base/dd.c:671
__device_attach_driver+0x1d8/0x290 drivers/base/dd.c:778
bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:454
__device_attach+0x223/0x3a0 drivers/base/dd.c:844
bus_probe_device+0x1f1/0x2a0 drivers/base/bus.c:514
device_add+0xad2/0x16e0 drivers/base/core.c:2106
usb_set_configuration+0xdf7/0x1740 drivers/usb/core/message.c:2021
generic_probe+0xa2/0xda drivers/usb/core/generic.c:210
usb_probe_device+0xc0/0x150 drivers/usb/core/driver.c:266
really_probe+0x2da/0xb10 drivers/base/dd.c:509
driver_probe_device+0x21d/0x350 drivers/base/dd.c:671
__device_attach_driver+0x1d8/0x290 drivers/base/dd.c:778
bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:454
__device_attach+0x223/0x3a0 drivers/base/dd.c:844
bus_probe_device+0x1f1/0x2a0 drivers/base/bus.c:514
device_add+0xad2/0x16e0 drivers/base/core.c:2106
usb_new_device.cold+0x537/0xccf drivers/usb/core/hub.c:2534
hub_port_connect drivers/usb/core/hub.c:5089 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
port_event drivers/usb/core/hub.c:5350 [inline]
hub_event+0x138e/0x3b00 drivers/usb/core/hub.c:5432
process_one_work+0x90f/0x1580 kernel/workqueue.c:2269
worker_thread+0x9b/0xe20 kernel/workqueue.c:2415
kthread+0x313/0x420 kernel/kthread.c:253
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Freed by task 12:
set_track mm/kasan/common.c:87 [inline]
__kasan_slab_free+0x130/0x180 mm/kasan/common.c:459
slab_free_hook mm/slub.c:1429 [inline]
slab_free_freelist_hook+0x5e/0x140 mm/slub.c:1456
slab_free mm/slub.c:3003 [inline]
kfree+0xce/0x290 mm/slub.c:3958
v4l2_device_release drivers/media/v4l2-core/v4l2-device.c:67 [inline]
kref_put include/linux/kref.h:67 [inline]
v4l2_device_put+0x7e/0xa0 drivers/media/v4l2-core/v4l2-device.c:72
cpia2_usb_disconnect+0x7e/0x1c0 drivers/media/usb/cpia2/cpia2_usb.c:905
usb_unbind_interface+0x1c9/0x980 drivers/usb/core/driver.c:423
__device_release_driver drivers/base/dd.c:1082 [inline]
device_release_driver_internal+0x436/0x4f0 drivers/base/dd.c:1113
bus_remove_device+0x302/0x5c0 drivers/base/bus.c:556
device_del+0x467/0xb90 drivers/base/core.c:2269
usb_disable_device+0x242/0x790 drivers/usb/core/message.c:1235
usb_disconnect+0x298/0x870 drivers/usb/core/hub.c:2197
hub_port_connect drivers/usb/core/hub.c:4940 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
port_event drivers/usb/core/hub.c:5350 [inline]
hub_event+0xcd2/0x3b00 drivers/usb/core/hub.c:5432
process_one_work+0x90f/0x1580 kernel/workqueue.c:2269
process_scheduled_works kernel/workqueue.c:2331 [inline]
worker_thread+0x7b0/0xe20 kernel/workqueue.c:2417
kthread+0x313/0x420 kernel/kthread.c:253
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff8880a09f0000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 2648 bytes inside of
4096-byte region [ffff8880a09f0000, ffff8880a09f1000)
The buggy address belongs to the page:
page:ffffea0002827c00 count:1 mapcount:0 mapping:ffff88812c3f4600 index:0x0
compound_mapcount: 0
flags: 0xfff00000010200(slab|head)
raw: 00fff00000010200 dead000000000100 dead000000000200 ffff88812c3f4600
raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880a09f0900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880a09f0980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8880a09f0a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880a09f0a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880a09f0b00: 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 can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: 7829a896 usb-fuzzer: main usb gadget fuzzer driver
git tree: https://github.com/google/kasan.git usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=11e19043a00000
kernel config: https://syzkaller.appspot.com/x/.config?x=f6d4561982f71f63

dashboard link: https://syzkaller.appspot.com/bug?extid=0c90fc937c84f97d0aa6
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=147d42eda00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=104c268ba00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+0c90fc...@syzkaller.appspotmail.com

cpia2: Message: count = 1, register[0] = 0x0
cpia2: Unexpected error: -19
==================================================================

BUG: KASAN: use-after-free in cpia2_usb_disconnect+0x1a4/0x1c0
drivers/media/usb/cpia2/cpia2_usb.c:898
Read of size 8 at addr ffff8881cf6c4e50 by task kworker/1:1/22

CPU: 1 PID: 22 Comm: kworker/1:1 Not tainted 5.2.0-rc6+ #13

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+0xca/0x13e lib/dump_stack.c:113
print_address_description+0x67/0x231 mm/kasan/report.c:188
__kasan_report.cold+0x1a/0x32 mm/kasan/report.c:317
kasan_report+0xe/0x20 mm/kasan/common.c:614
cpia2_usb_disconnect+0x1a4/0x1c0 drivers/media/usb/cpia2/cpia2_usb.c:898
usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
__device_release_driver drivers/base/dd.c:1081 [inline]
device_release_driver_internal+0x404/0x4c0 drivers/base/dd.c:1112
bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:556
device_del+0x460/0xb80 drivers/base/core.c:2274
usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
usb_disconnect+0x284/0x830 drivers/usb/core/hub.c:2197

hub_port_connect drivers/usb/core/hub.c:4940 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
port_event drivers/usb/core/hub.c:5350 [inline]

hub_event+0x1409/0x3590 drivers/usb/core/hub.c:5432
process_one_work+0x905/0x1570 kernel/workqueue.c:2269
process_scheduled_works kernel/workqueue.c:2331 [inline]
worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
kthread+0x30b/0x410 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:71
set_track mm/kasan/common.c:79 [inline]
__kasan_kmalloc mm/kasan/common.c:489 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:462

kmalloc include/linux/slab.h:547 [inline]
kzalloc include/linux/slab.h:742 [inline]

cpia2_init_camera_struct+0x40/0x110
drivers/media/usb/cpia2/cpia2_core.c:2176
cpia2_usb_probe.cold+0x37/0x45a drivers/media/usb/cpia2/cpia2_usb.c:833
usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
really_probe+0x281/0x660 drivers/base/dd.c:509
driver_probe_device+0x104/0x210 drivers/base/dd.c:670
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:777
bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
__device_attach+0x217/0x360 drivers/base/dd.c:843
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
device_add+0xae6/0x16f0 drivers/base/core.c:2111
usb_set_configuration+0xdf6/0x1670 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+0x281/0x660 drivers/base/dd.c:509
driver_probe_device+0x104/0x210 drivers/base/dd.c:670
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:777
bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
__device_attach+0x217/0x360 drivers/base/dd.c:843
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
device_add+0xae6/0x16f0 drivers/base/core.c:2111
usb_new_device.cold+0x8c1/0x1016 drivers/usb/core/hub.c:2534

hub_port_connect drivers/usb/core/hub.c:5089 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
port_event drivers/usb/core/hub.c:5350 [inline]

hub_event+0x1ada/0x3590 drivers/usb/core/hub.c:5432
process_one_work+0x905/0x1570 kernel/workqueue.c:2269
worker_thread+0x96/0xe20 kernel/workqueue.c:2415
kthread+0x30b/0x410 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 22:
save_stack+0x1b/0x80 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_slab_free+0x130/0x180 mm/kasan/common.c:451
slab_free_hook mm/slub.c:1421 [inline]
slab_free_freelist_hook mm/slub.c:1448 [inline]
slab_free mm/slub.c:2994 [inline]
kfree+0xd7/0x280 mm/slub.c:3949
v4l2_device_release drivers/media/v4l2-core/v4l2-device.c:55 [inline]
kref_put include/linux/kref.h:65 [inline]
v4l2_device_put+0x76/0x90 drivers/media/v4l2-core/v4l2-device.c:60
cpia2_usb_disconnect+0x79/0x1c0 drivers/media/usb/cpia2/cpia2_usb.c:896
usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
__device_release_driver drivers/base/dd.c:1081 [inline]
device_release_driver_internal+0x404/0x4c0 drivers/base/dd.c:1112
bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:556
device_del+0x460/0xb80 drivers/base/core.c:2274
usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
usb_disconnect+0x284/0x830 drivers/usb/core/hub.c:2197

hub_port_connect drivers/usb/core/hub.c:4940 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
port_event drivers/usb/core/hub.c:5350 [inline]

hub_event+0x1409/0x3590 drivers/usb/core/hub.c:5432
process_one_work+0x905/0x1570 kernel/workqueue.c:2269
process_scheduled_works kernel/workqueue.c:2331 [inline]
worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
kthread+0x30b/0x410 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff8881cf6c4400

which belongs to the cache kmalloc-4k of size 4096

The buggy address is located 2640 bytes inside of
4096-byte region [ffff8881cf6c4400, ffff8881cf6c5400)

The buggy address belongs to the page:

page:ffffea00073db000 refcount:1 mapcount:0 mapping:ffff8881dac02600
index:0x0 compound_mapcount: 0
flags: 0x200000000010200(slab|head)
raw: 0200000000010200 0000000000000000 0000000100000001 ffff8881dac02600

raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff8881cf6c4d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881cf6c4d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8881cf6c4e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8881cf6c4e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881cf6c4f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

[Oliver Neukum]

Am Dienstag, den 02.07.2019, 18:01 -0700 schrieb syzbot:
> syzbot has found a reproducer for the following crash on:
>
> HEAD commit: 7829a896 usb-fuzzer: main usb gadget fuzzer driver
> git tree: https://github.com/google/kasan.git usb-fuzzer
> console output: https://syzkaller.appspot.com/x/log.txt?x=11e19043a00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=f6d4561982f71f63
> dashboard link: https://syzkaller.appspot.com/bug?extid=0c90fc937c84f97d0aa6
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=147d42eda00000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=104c268ba00000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+0c90fc...@syzkaller.appspotmail.com
>
> cpia2: Message: count = 1, register[0] = 0x0
> cpia2: Unexpected error: -19
> ==================================================================
> BUG: KASAN: use-after-free in cpia2_usb_disconnect+0x1a4/0x1c0
> drivers/media/usb/cpia2/cpia2_usb.c:898
> Read of size 8 at addr ffff8881cf6c4e50 by task kworker/1:1/22

Please try this:

From a0a73298fc23acb95e7b6487e960be707563eb34 Mon Sep 17 00:00:00 2001
From: Oliver Neukum <one...@suse.com>
Date: Wed, 8 May 2019 12:36:40 +0200
Subject: [PATCH] cpia2_usb: first wake up, then free in disconnect

Kasan reported a use after free in cpia2_usb_disconnect()
It first freed everything and then woke up those waiting.
The reverse order is correct.

Signed-off-by: Oliver Neukum <one...@suse.com>
Reported-by: syzbot+0c90fc...@syzkaller.appspotmail.com
Fixes: 6c493f8b28c67 ("[media] cpia2: major overhaul to get it in a working state again")
---
drivers/media/usb/cpia2/cpia2_usb.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/cpia2/cpia2_usb.c b/drivers/media/usb/cpia2/cpia2_usb.c
index e5d8dee38fe4..44bd7e5ad3eb 100644
--- a/drivers/media/usb/cpia2/cpia2_usb.c
+++ b/drivers/media/usb/cpia2/cpia2_usb.c
@@ -902,7 +902,6 @@ static void cpia2_usb_disconnect(struct usb_interface *intf)
cpia2_unregister_camera(cam);
v4l2_device_disconnect(&cam->v4l2_dev);
mutex_unlock(&cam->v4l2_lock);
- v4l2_device_put(&cam->v4l2_dev);

if(cam->buffers) {
DBG("Wakeup waiting processes\n");
@@ -911,6 +910,8 @@ static void cpia2_usb_disconnect(struct usb_interface *intf)
wake_up_interruptible(&cam->wq_stream);
}

+ v4l2_device_put(&cam->v4l2_dev);
+
LOG("CPiA2 camera disconnected.\n");
}

--
2.16.4

[Eric Biggers]

On Wed, Jul 03, 2019 at 09:42:09AM +0200, Oliver Neukum wrote:
> Am Dienstag, den 02.07.2019, 18:01 -0700 schrieb syzbot:
> > syzbot has found a reproducer for the following crash on:
> >
> > HEAD commit: 7829a896 usb-fuzzer: main usb gadget fuzzer driver
> > git tree: https://github.com/google/kasan.git usb-fuzzer
> > console output: https://syzkaller.appspot.com/x/log.txt?x=11e19043a00000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=f6d4561982f71f63
> > dashboard link: https://syzkaller.appspot.com/bug?extid=0c90fc937c84f97d0aa6
> > compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=147d42eda00000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=104c268ba00000
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+0c90fc...@syzkaller.appspotmail.com
> >
> > cpia2: Message: count = 1, register[0] = 0x0
> > cpia2: Unexpected error: -19
> > ==================================================================
> > BUG: KASAN: use-after-free in cpia2_usb_disconnect+0x1a4/0x1c0
> > drivers/media/usb/cpia2/cpia2_usb.c:898
> > Read of size 8 at addr ffff8881cf6c4e50 by task kworker/1:1/22
>
> Please try this:
>
> From a0a73298fc23acb95e7b6487e960be707563eb34 Mon Sep 17 00:00:00 2001
> From: Oliver Neukum <one...@suse.com>
> Date: Wed, 8 May 2019 12:36:40 +0200
> Subject: [PATCH] cpia2_usb: first wake up, then free in disconnect
>

Who are you talking to? If you want syzbot to test your patch, follow the
directions at https://github.com/google/syzkaller/blob/master/docs/syzbot.md#testing-patches

- Eric

[Oliver Neukum]

Am Mittwoch, den 03.07.2019, 10:10 -0700 schrieb Eric Biggers:
>
> Who are you talking to? If you want syzbot to test your patch, follow the
> directions at https://github.com/google/syzkaller/blob/master/docs/syzbot.md#testing-patches

Thanks. I am trying this out now.

Regards
Oliver

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger
crash:

Reported-and-tested-by:
syzbot+0c90fc...@syzkaller.appspotmail.com

Tested on:

commit: 7829a896 usb-fuzzer: main usb gadget fuzzer driver
git tree: https://github.com/google/kasan.git usb-fuzzer

kernel config: https://syzkaller.appspot.com/x/.config?x=f6d4561982f71f63

compiler: gcc (GCC) 9.0.0 20181231 (experimental)

patch: https://syzkaller.appspot.com/x/patch.diff?x=17b2d93ba00000

Note: testing is done by a robot and is best-effort only.