On Thu, Aug 29, 2013 at 2:48 AM, Benjamin Tissoires
<benjamin.tissoires@xxxxxxxxx> wrote:
> On Wed, Aug 28, 2013 at 10:30 PM, Jiri Kosina <jkosina@xxxxxxx> wrote:
>> From: Kees Cook <keescook@xxxxxxxxxxxx>
>>
>> This driver must validate the availability of the HID output report and
>> its size before it can write LED states via buzz_set_leds(). This stops
>> a heap overflow that is possible if a device provides a malicious HID
>> output report:
>>
>> [ 108.171280] usb 1-1: New USB device found, idVendor=054c, idProduct=0002
>> ...
>> [ 117.507877] BUG kmalloc-192 (Not tainted): Redzone overwritten
>>
>> CVE-2013-2890
>>
>> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
>> Cc: stable@xxxxxxxxxx
>> ---
>> drivers/hid/hid-sony.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/hid/hid-sony.c b/drivers/hid/hid-sony.c
>> index 87fbe29..b987926 100644
>> --- a/drivers/hid/hid-sony.c
>> +++ b/drivers/hid/hid-sony.c
>> @@ -537,6 +537,10 @@ static int buzz_init(struct hid_device *hdev)
>> drv_data = hid_get_drvdata(hdev);
>> BUG_ON(!(drv_data->quirks & BUZZ_CONTROLLER));
>>
>> + /* Validate expected report characteristics. */
>> + if (!hid_validate_report(hdev, HID_OUTPUT_REPORT, 0, 1, 7))
>
> I don't have access to the device anymore, but I still kept the report
> descriptors (this is the interesting part):
>
> 0xa1, 0x02, // Collection (Logical) 60
> 0x75, 0x08, // Report Size (8) 62
> 0x95, 0x07, // Report Count (7) 64
> 0x46, 0xff, 0x00, // Physical Maximum (255) 66
> 0x26, 0xff, 0x00, // Logical Maximum (255) 69
> 0x09, 0x02, // Usage (Vendor Usage 2) 72
> 0x91, 0x02, // Output (Data,Var,Abs) 74
> 0xc0, // End Collection 76
>
> So with the current implementation of hid_validate_report(), it works,
> but if another Buzz controller show up at some point with extras
> fields in this output report... we will be screwed. So please, amend
> hid_validate_report(), or specifically test here that the LED output
> report is 7 bytes.
hid_validate_report() checks for "at least" 7 in this call, so it
should be fine, unless I've misunderstood something.
-Kees
>
> Cheers,
> Benjamin
>
>> + return -ENODEV;
>> +
>> buzz = kzalloc(sizeof(*buzz), GFP_KERNEL);
>> if (!buzz) {
>> hid_err(hdev, "Insufficient memory, cannot allocate driver data\n");
>>
>> --
>> Jiri Kosina
>> SUSE Labs
>> --
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--
Kees Cook
Chrome OS Security
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