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SubjectRe: [PATCH] au0828: fix use-after-free at USB probing
On Fri, Nov 10, 2017 at 6:35 PM, Gustavo A. R. Silva
<garsilva@embeddedor.com> wrote:
>
> Quoting Andrey Konovalov <andreyknvl@google.com>:
>
>> On Fri, Nov 10, 2017 at 1:21 AM, Gustavo A. R. Silva
>> <garsilva@embeddedor.com> wrote:
>>>
>>> Hi Andrey,
>>>
>>> Could you please try this patch?
>>>
>>> Thank you

Hi!

Sorry for the delay.

With this patch I still see the same report:

au0828: recv_control_msg() Failed receiving control message, error -71.
au0828: recv_control_msg() Failed receiving control message, error -71.
au0828: recv_control_msg() Failed receiving control message, error -71.
au8522_writereg: writereg error (reg == 0x106, val == 0x0001, ret == -5)
usb 1-1: selecting invalid altsetting 5
au0828: Failure setting usb interface0 to as5
au0828: au0828_usb_probe() au0282_dev_register failed to register on V4L2
au0828: probe of 1-1:0.0 failed with error -22
usb 1-1: USB disconnect, device number 3
==================================================================
BUG: KASAN: use-after-free in __list_del_entry_valid+0xda/0xf3
Read of size 8 at addr ffff880062a74410 by task kworker/0:1/24

CPU: 0 PID: 24 Comm: kworker/0:1 Not tainted
4.14.0-rc8-44455-ge2105594a876-dirty #111
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
__dump_stack lib/dump_stack.c:17
dump_stack+0xe1/0x157 lib/dump_stack.c:53
print_address_description+0x71/0x234 mm/kasan/report.c:252
kasan_report_error mm/kasan/report.c:351
kasan_report+0x173/0x270 mm/kasan/report.c:409
__asan_report_load8_noabort+0x19/0x20 mm/kasan/report.c:430
__list_del_entry_valid+0xda/0xf3 lib/list_debug.c:54
__list_del_entry ./include/linux/list.h:117
list_del_init ./include/linux/list.h:159
device_pm_remove+0x4a/0x1e7 drivers/base/power/main.c:149
device_del+0x599/0xa70 drivers/base/core.c:1986
usb_disable_device+0x223/0x710 drivers/usb/core/message.c:1170
usb_disconnect+0x285/0x7f0 drivers/usb/core/hub.c:2205
hub_port_connect drivers/usb/core/hub.c:4838
hub_port_connect_change drivers/usb/core/hub.c:5093
port_event drivers/usb/core/hub.c:5199
hub_event_impl+0x10ec/0x3440 drivers/usb/core/hub.c:5311
hub_event+0x38/0x50 drivers/usb/core/hub.c:5209
process_one_work+0x925/0x15d0 kernel/workqueue.c:2113
process_scheduled_works kernel/workqueue.c:2173
worker_thread+0x72e/0x10d0 kernel/workqueue.c:2249
kthread+0x346/0x410 kernel/kthread.c:231
ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:432

The buggy address belongs to the page:
page:ffffea00018a9d00 count:0 mapcount:-127 mapping: (null) index:0x0
flags: 0x100000000000000()
raw: 0100000000000000 0000000000000000 0000000000000000 00000000ffffff80
raw: ffff88007fffa690 ffffea00018e6120 0000000000000002 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff880062a74300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff880062a74380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff880062a74400: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff880062a74480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff880062a74500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
=================================================================

Thanks!

>>
>>
>> Hi Gustavo,
>>
>> With your patch I get a different crash. Not sure if it's another bug
>> or the same one manifesting differently.
>>
>
> That's the same one. It seems that the best solution is to remove the kfree
> after the mutex_unlock and let the device resources be freed in
> au0828_usb_disconnect.
>
> Please try the following patch instead.
>
> I appreciate your help.
>
> Thank you, Andrey.
>
> ---
> drivers/media/usb/au0828/au0828-core.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/drivers/media/usb/au0828/au0828-core.c
> b/drivers/media/usb/au0828/au0828-core.c
> index cd363a2..257ae0d 100644
> --- a/drivers/media/usb/au0828/au0828-core.c
> +++ b/drivers/media/usb/au0828/au0828-core.c
> @@ -629,7 +629,6 @@ static int au0828_usb_probe(struct usb_interface
> *interface,
> pr_err("%s() au0282_dev_register failed to register on
> V4L2\n",
> __func__);
> mutex_unlock(&dev->lock);
> - kfree(dev);
> goto done;
> }
>
> --
> 2.7.4
>
>
>> au0828: recv_control_msg() Failed receiving control message, error -71.
>> au0828: recv_control_msg() Failed receiving control message, error -71.
>> au8522_writereg: writereg error (reg == 0x106, val == 0x0001, ret == -5)
>> usb 1-1: selecting invalid altsetting 5
>> au0828: Failure setting usb interface0 to as5
>> au0828: au0828_usb_probe() au0282_dev_register failed to register on V4L2
>> au0828: probe of 1-1:0.0 failed with error -22
>> usb 1-1: USB disconnect, device number 2
>> ==================================================================
>> BUG: KASAN: use-after-free in __list_del_entry_valid+0xda/0xf3
>> Read of size 8 at addr ffff8800641d0410 by task kworker/0:1/24
>>
>> CPU: 0 PID: 24 Comm: kworker/0:1 Not tainted
>> 4.14.0-rc5-43687-g72e555fa3d2e-dirty #105
>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs
>> 01/01/2011
>> Workqueue: usb_hub_wq hub_event
>> Call Trace:
>> __dump_stack lib/dump_stack.c:16
>> dump_stack+0xc1/0x11f lib/dump_stack.c:52
>> print_address_description+0x71/0x234 mm/kasan/report.c:252
>> kasan_report_error mm/kasan/report.c:351
>> kasan_report+0x173/0x270 mm/kasan/report.c:409
>> __asan_report_load8_noabort+0x19/0x20 mm/kasan/report.c:430
>> __list_del_entry_valid+0xda/0xf3 lib/list_debug.c:54
>> __list_del_entry ./include/linux/list.h:116
>> list_del_init ./include/linux/list.h:158
>> device_pm_remove+0x4a/0x1da drivers/base/power/main.c:149
>> device_del+0x55f/0xa30 drivers/base/core.c:1986
>> usb_disable_device+0x1df/0x670 drivers/usb/core/message.c:1170
>> usb_disconnect+0x260/0x7a0 drivers/usb/core/hub.c:2124
>> hub_port_connect drivers/usb/core/hub.c:4754
>> hub_port_connect_change drivers/usb/core/hub.c:5009
>> port_event drivers/usb/core/hub.c:5115
>> hub_event+0xe09/0x2eb0 drivers/usb/core/hub.c:5195
>> process_one_work+0x86d/0x13e0 kernel/workqueue.c:2119
>> process_scheduled_works kernel/workqueue.c:2179
>> worker_thread+0x689/0xea0 kernel/workqueue.c:2255
>> kthread+0x334/0x400 kernel/kthread.c:231
>> ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431
>>
>> The buggy address belongs to the page:
>> page:ffffea0001907400 count:0 mapcount:-127 mapping: (null)
>> index:0x0
>> flags: 0x100000000000000()
>> raw: 0100000000000000 0000000000000000 0000000000000000 00000000ffffff80
>> raw: ffffea00018a8f20 ffff88007fffa690 0000000000000002 0000000000000000
>> page dumped because: kasan: bad access detected
>>
>> Memory state around the buggy address:
>> ffff8800641d0300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>> ffff8800641d0380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>>>
>>> ffff8800641d0400: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>>
>> ^
>> ffff8800641d0480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>> ffff8800641d0500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>> ==================================================================
>>
>> Thanks!
>>
>>>
>>>
>>> The device is typically freed on failure after trying to set
>>> USB interface0 to as5 in function au0828_analog_register.
>>>
>>> Fix use-after-free by returning the error value inmediately
>>> after failure, instead of jumping to au0828_usb_disconnect
>>> where _dev_ is also freed.
>>>
>>> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
>>> ---
>>> drivers/media/usb/au0828/au0828-core.c | 3 +--
>>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/media/usb/au0828/au0828-core.c
>>> b/drivers/media/usb/au0828/au0828-core.c
>>> index cd363a2..b4abd90 100644
>>> --- a/drivers/media/usb/au0828/au0828-core.c
>>> +++ b/drivers/media/usb/au0828/au0828-core.c
>>> @@ -630,7 +630,7 @@ static int au0828_usb_probe(struct usb_interface
>>> *interface,
>>> __func__);
>>> mutex_unlock(&dev->lock);
>>> kfree(dev);
>>> - goto done;
>>> + return retval;
>>> }
>>>
>>> /* Digital TV */
>>> @@ -655,7 +655,6 @@ static int au0828_usb_probe(struct usb_interface
>>> *interface,
>>>
>>> retval = au0828_media_device_register(dev, usbdev);
>>>
>>> -done:
>>> if (retval < 0)
>>> au0828_usb_disconnect(interface);
>>>
>>> --
>>> 2.7.4
>>>
>
>
>
>
>
>

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