ALSA: usb-audio: Validate UAC3 cluster segment descriptors

UAC3 class segment descriptors need to be verified whether their sizes
match with the declared lengths and whether they fit with the
allocated buffer sizes, too.  Otherwise malicious firmware may lead to
the unexpected OOB accesses.

Fixes: 11785ef ("ALSA: usb-audio: Initial Power Domain 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]>

Author: tiwai

sound/usb/stream.c

@@ -341,20 +341,28 @@ snd_pcm_chmap_elem *convert_chmap_v3(struct uac3_cluster_header_descriptor
 
 	len = le16_to_cpu(cluster->wLength);
 	c = 0;
-	p += sizeof(struct uac3_cluster_header_descriptor);
+	p += sizeof(*cluster);
+	len -= sizeof(*cluster);
 
-	while (((p - (void *)cluster) < len) && (c < channels)) {
+	while (len > 0 && (c < channels)) {
 		struct uac3_cluster_segment_descriptor *cs_desc = p;
 		u16 cs_len;
 		u8 cs_type;
 
+		if (len < sizeof(*p))
+			break;
 		cs_len = le16_to_cpu(cs_desc->wLength);
+		if (len < cs_len)
+			break;
 		cs_type = cs_desc->bSegmentType;
 
 		if (cs_type == UAC3_CHANNEL_INFORMATION) {
 			struct uac3_cluster_information_segment_descriptor *is = p;
 			unsigned char map;
 
+			if (cs_len < sizeof(*is))
+				break;
+
 			/*
 			 * TODO: this conversion is not complete, update it
 			 * after adding UAC3 values to asound.h
@@ -456,6 +464,7 @@ snd_pcm_chmap_elem *convert_chmap_v3(struct uac3_cluster_header_descriptor
 			chmap->map[c++] = map;
 		}
 		p += cs_len;
+		len -= cs_len;
 	}
 
 	if (channels < c)
@@ -881,7 +890,7 @@ snd_usb_get_audioformat_uac3(struct snd_usb_audio *chip,
 	u64 badd_formats = 0;
 	unsigned int num_channels;
 	struct audioformat *fp;
-	u16 cluster_id, wLength;
+	u16 cluster_id, wLength, cluster_wLength;
 	int clock = 0;
 	int err;
 
@@ -1011,6 +1020,16 @@ snd_usb_get_audioformat_uac3(struct snd_usb_audio *chip,
 		return ERR_PTR(-EIO);
 	}
 
+	cluster_wLength = le16_to_cpu(cluster->wLength);
+	if (cluster_wLength < sizeof(*cluster) ||
+	    cluster_wLength > wLength) {
+		dev_err(&dev->dev,
+			"%u:%d : invalid Cluster Descriptor size\n",
+			iface_no, altno);
+		kfree(cluster);
+		return ERR_PTR(-EIO);
+	}
+
 	num_channels = cluster->bNrChannels;
 	chmap = convert_chmap_v3(cluster);
 	kfree(cluster);