The `uac_mixer_unit_descriptor` shown as below is read from the
device side. In `parse_audio_mixer_unit`, `baSourceID` field is
accessed from index 0 to `bNrInPins` - 1, the current implementation
assumes that descriptor is always valid (the length of descriptor
is no shorter than 5 + `bNrInPins`). If a descriptor read from
the device side is invalid, it may trigger out-of-bound memory
access.
```
struct uac_mixer_unit_descriptor {
__u8 bLength;
__u8 bDescriptorType;
__u8 bDescriptorSubtype;
__u8 bUnitID;
__u8 bNrInPins;
__u8 baSourceID[];
}
```
This patch fixes the bug by add a sanity check on the length of
the descriptor.
CVE: CVE-2018-15117
Reported-by: Hui Peng <[email protected]>
Reported-by: Mathias Payer <[email protected]>
Signed-off-by: Hui Peng <[email protected]>
---
sound/usb/mixer.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 1f7eb3816cd7..10ddec76f906 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1628,6 +1628,7 @@ static int parse_audio_mixer_unit(struct mixer_build *state, int unitid,
int pin, ich, err;
if (desc->bLength < 11 || !(input_pins = desc->bNrInPins) ||
+ desc->bLength < sizeof(*desc) + desc->bNrInPins ||
!(num_outs = uac_mixer_unit_bNrChannels(desc))) {
usb_audio_err(state->chip,
"invalid MIXER UNIT descriptor %d\n",
--
2.17.1
On Fri, Aug 30, 2019 at 05:46:49PM -0400, Hui Peng wrote:
> The `uac_mixer_unit_descriptor` shown as below is read from the
> device side. In `parse_audio_mixer_unit`, `baSourceID` field is
> accessed from index 0 to `bNrInPins` - 1, the current implementation
> assumes that descriptor is always valid (the length of descriptor
> is no shorter than 5 + `bNrInPins`). If a descriptor read from
> the device side is invalid, it may trigger out-of-bound memory
> access.
>
> ```
> struct uac_mixer_unit_descriptor {
> __u8 bLength;
> __u8 bDescriptorType;
> __u8 bDescriptorSubtype;
> __u8 bUnitID;
> __u8 bNrInPins;
> __u8 baSourceID[];
> }
> ```
>
> This patch fixes the bug by add a sanity check on the length of
> the descriptor.
>
> CVE: CVE-2018-15117
FWIW, the correct CVE id should be probably CVE-2019-15117 here.
But there was already a patch queued and released in 5.2.10 and
4.19.68 for this issue (as far I can see; is this correct?)
Regards,
Salvatore
On 9/1/19 8:58 AM, Salvatore Bonaccorso wrote:
> On Fri, Aug 30, 2019 at 05:46:49PM -0400, Hui Peng wrote:
>> The `uac_mixer_unit_descriptor` shown as below is read from the
>> device side. In `parse_audio_mixer_unit`, `baSourceID` field is
>> accessed from index 0 to `bNrInPins` - 1, the current implementation
>> assumes that descriptor is always valid (the length of descriptor
>> is no shorter than 5 + `bNrInPins`). If a descriptor read from
>> the device side is invalid, it may trigger out-of-bound memory
>> access.
>>
>> ```
>> struct uac_mixer_unit_descriptor {
>> __u8 bLength;
>> __u8 bDescriptorType;
>> __u8 bDescriptorSubtype;
>> __u8 bUnitID;
>> __u8 bNrInPins;
>> __u8 baSourceID[];
>> }
>> ```
>>
>> This patch fixes the bug by add a sanity check on the length of
>> the descriptor.
>>
>> CVE: CVE-2018-15117
> FWIW, the correct CVE id should be probably CVE-2019-15117 here.
Yes, the CVE id was wrong. I have updated it in the attached patch.
> But there was already a patch queued and released in 5.2.10 and
> 4.19.68 for this issue (as far I can see; is this correct?)
Yes, it should have been fixed in those branches.
But google asked me to back port it to v4.4.190 and v4.14.141.
I have mentioned it in one previous email, but it was blocked by vger
because it was sent in html format.
Can you apply it to these 2 versions? (it applies to both versions)
Thanks.
> Regards,
> Salvatore
On Fri, Aug 30, 2019 at 05:49:59PM -0400, Hui Peng wrote:
> This is the backported patch of the following bug to v4.4.x and v4.14.x:
> daac07156b33 ("ALSA: usb-audio: Fix an OOB bug in parse_audio_mixer_unit")
Thanks, also now queued up to 4.9.y, you forgot that one :)
greg k-h