From 70350d071df08456f582bc55abbab1fe888aadaa Mon Sep 17 00:00:00 2001 From: Hui Peng Date: Tue, 13 Aug 2019 22:34:04 -0400 Subject: [PATCH] ALSA: usb-audio: Fix an OOB bug in parse_audio_mixer_unit commit daac07156b330b18eb5071aec4b3ddca1c377f2c upstream. 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. Change-Id: Ifa5b3c5177dd5a3c93e4523516014664313e7523 Reported-by: Hui Peng Reported-by: Mathias Payer Signed-off-by: Hui Peng Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- sound/usb/mixer.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c index 8236760464b1..4c9cac78aa72 100644 --- a/sound/usb/mixer.c +++ b/sound/usb/mixer.c @@ -1528,7 +1528,9 @@ static int parse_audio_mixer_unit(struct mixer_build *state, int unitid, void *r int input_pins, num_ins, num_outs; int pin, ich, err; - if (desc->bLength < 11 || ! (input_pins = desc->bNrInPins) || ! (num_outs = uac_mixer_unit_bNrChannels(desc))) { + if (desc->bLength < 11 || !(input_pins = desc->bNrInPins) || + desc->bLength < sizeof(*desc) + desc->bNrInPins || + !(num_outs = uac_mixer_unit_bNrChannels(desc))) { snd_printk(KERN_ERR "invalid MIXER UNIT descriptor %d\n", unitid); return -EINVAL; }