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

jira VULN-136368
cve CVE-2025-38729
commit-author Takashi Iwai <tiwai@suse.de>
commit d832ccb

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 <yjjuny.lee@samsung.com>
	Cc: <stable@vger.kernel.org>
Link: https://patch.msgid.link/20250814081245.8902-1-tiwai@suse.de
	Signed-off-by: Takashi Iwai <tiwai@suse.de>
(cherry picked from commit d832ccb)
	Signed-off-by: Roxana Nicolescu <rnicolescu@ciq.com>

Author: roxanan1996

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 */
 };