ALSA: usb-audio: Validate UAC3 power domain descriptors, too

commit d832ccb upstream.

UAC3 power domain descriptors need to be verified with its variable
bLength for avoiding the unexpected OOB accesses by malicious
firmware, too.

Fixes: 9a2fe9b ("ALSA: usb: initial USB Audio Device Class 3.0 support")
Reported-and-tested-by: Youngjun Lee <[email protected]>
Cc: <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Takashi Iwai <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: tiwai

sound/usb/validate.c

@@ -221,6 +221,17 @@ static bool validate_uac3_feature_unit(const void *p,
 	return d->bLength >= sizeof(*d) + 4 + 2;
 }
 
+static bool validate_uac3_power_domain_unit(const void *p,
+					    const struct usb_desc_validator *v)
+{
+	const struct uac3_power_domain_descriptor *d = p;
+
+	if (d->bLength < sizeof(*d))
+		return false;
+	/* baEntities[] + wPDomainDescrStr */
+	return d->bLength >= sizeof(*d) + d->bNrEntities + 2;
+}
+
 static bool validate_midi_out_jack(const void *p,
 				   const struct usb_desc_validator *v)
 {
@@ -285,6 +296,7 @@ static const struct usb_desc_validator audio_validators[] = {
 	      struct uac3_clock_multiplier_descriptor),
 	/* UAC_VERSION_3, UAC3_SAMPLE_RATE_CONVERTER: not implemented yet */
 	/* UAC_VERSION_3, UAC3_CONNECTORS: not implemented yet */
+	FUNC(UAC_VERSION_3, UAC3_POWER_DOMAIN, validate_uac3_power_domain_unit),
 	{ } /* terminator */
 };