ALSA: usb-audio: Avoid potential endless loop in convert_chmap_v3()

commit 6e7247d upstream.

The convert_chmap_v3() has a loop with its increment size of
cs_desc->wLength, but we forgot to validate cs_desc->wLength itself,
which may lead to potential endless loop by a malformed descriptor.

Add a proper size check to abort the loop for plugging the hole.

Fixes: ecfd411 ("ALSA: usb-audio: Validate UAC3 cluster segment descriptors")
Cc: <stable@vger.kernel.org>
Link: https://patch.msgid.link/20260427152224.15276-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: tiwai

sound/usb/stream.c

@@ -352,6 +352,8 @@ snd_pcm_chmap_elem *convert_chmap_v3(struct uac3_cluster_header_descriptor
 		if (len < sizeof(*cs_desc))
 			break;
 		cs_len = le16_to_cpu(cs_desc->wLength);
+		if (cs_len < sizeof(*cs_desc))
+			break;
 		if (len < cs_len)
 			break;
 		cs_type = cs_desc->bSegmentType;