On Fri, Apr 6, 2018 at 2:41 AM, Ruslan Bilovol <ruslan.bilovol@xxxxxxxxx> wrote:
> Hi Takashi,
>
> On Thu, Apr 5, 2018 at 3:11 PM, Takashi Iwai <tiwai@xxxxxxx> wrote:
>> The sanity checks introduced for malformed descriptors loosely check
>> the given descriptor size, although the size greater than the defined
>> description is invalid. It was due to a concern of any funky firmware
>> in the actual products. But this doesn't look hitting, and any sane
>> products must have the defined descriptors.
>>
>> So in this patch, we make the validators more strict, allowing only
>> with the defined descriptor sizes.
>>
>> Suggested-by: Ruslan Bilovol <ruslan.bilovol@xxxxxxxxx>
>> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
>> ---
>> sound/usb/clock.c | 6 +++---
>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/sound/usb/clock.c b/sound/usb/clock.c
>> index 27c2275a2505..cbf68ab01836 100644
>> --- a/sound/usb/clock.c
>> +++ b/sound/usb/clock.c
>> @@ -52,7 +52,7 @@ static void *find_uac_clock_desc(struct usb_host_interface *iface, int id,
>> static bool validate_clock_source_v2(void *p, int id)
>> {
>> struct uac_clock_source_descriptor *cs = p;
>> - return cs->bLength >= sizeof(*cs) && cs->bClockID == id;
>> + return cs->bLength == sizeof(*cs) && cs->bClockID == id;
Also I tested scenario which uses only this function (validate_clock_source_v2)
and it works fine to me.
>> }
>>
>> static bool validate_clock_source_v3(void *p, int id)
>> @@ -65,7 +65,7 @@ static bool validate_clock_selector_v2(void *p, int id)
>> {
>> struct uac_clock_selector_descriptor *cs = p;
>> return cs->bLength >= sizeof(*cs) && cs->bClockID == id &&
>> - cs->bLength >= 5 + cs->bNrInPins;
>> + cs->bLength == 5 + cs->bNrInPins;
>
> This one still has an issue, here we should check it next way:
> cs->bLength == 7 + cs->bNrInPins;
>
> This is because bLength is 7+bNrInPins as per UAC2 spec, not 5 :P
>
> Thanks,
> Ruslan
>
>> }
>>
>> static bool validate_clock_selector_v3(void *p, int id)
>> @@ -77,7 +77,7 @@ static bool validate_clock_selector_v3(void *p, int id)
>> static bool validate_clock_multiplier_v2(void *p, int id)
>> {
>> struct uac_clock_multiplier_descriptor *cs = p;
>> - return cs->bLength >= sizeof(*cs) && cs->bClockID == id;
>> + return cs->bLength == sizeof(*cs) && cs->bClockID == id;
>> }
>>
>> static bool validate_clock_multiplier_v3(void *p, int id)
>> --
>> 2.16.2
>>
--
Best regards,
Ruslan Bilovol
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