From: Hui Peng Date: Tue, 13 Aug 2019 22:34:04 -0400 Subject: ALSA: usb-audio: Fix an OOB bug in parse_audio_mixer_unit Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2019-15117 Origin: https://git.kernel.org/linus/daac07156b330b18eb5071aec4b3ddca1c377f2c 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. Reported-by: Hui Peng Reported-by: Mathias Payer Cc: Signed-off-by: Hui Peng Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/usb/mixer.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c index 996126a28072..4b3e1c48ca2f 100644 --- a/sound/usb/mixer.c +++ b/sound/usb/mixer.c @@ -760,6 +760,8 @@ static int uac_mixer_unit_get_channels(struct mixer_build *state, return -EINVAL; if (!desc->bNrInPins) return -EINVAL; + if (desc->bLength < sizeof(*desc) + desc->bNrInPins) + return -EINVAL; switch (state->mixer->protocol) { case UAC_VERSION_1: -- cgit 1.2-0.3.lf.el7