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")
On Fri, Aug 30, 2019 at 5:47 PM Hui Peng benquike@gmail.com 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
Reported-by: Hui Peng benquike@gmail.com Reported-by: Mathias Payer mathias.payer@nebelwelt.net Signed-off-by: Hui Peng benquike@gmail.com
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