Commit daac0715 authored by Hui Peng's avatar Hui Peng Committed by Takashi Iwai

ALSA: usb-audio: Fix an OOB bug in parse_audio_mixer_unit

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: default avatarHui Peng <benquike@gmail.com>
Reported-by: default avatarMathias Payer <mathias.payer@nebelwelt.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarHui Peng <benquike@gmail.com>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 871b9066
...@@ -744,6 +744,8 @@ static int uac_mixer_unit_get_channels(struct mixer_build *state, ...@@ -744,6 +744,8 @@ static int uac_mixer_unit_get_channels(struct mixer_build *state,
return -EINVAL; return -EINVAL;
if (!desc->bNrInPins) if (!desc->bNrInPins)
return -EINVAL; return -EINVAL;
if (desc->bLength < sizeof(*desc) + desc->bNrInPins)
return -EINVAL;
switch (state->mixer->protocol) { switch (state->mixer->protocol) {
case UAC_VERSION_1: case UAC_VERSION_1:
......
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