Re: [PATCH 1/2] Fix an OOB bug in parse_audio_mixer_unit

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