ALSA: usb-audio: Fix size validation in convert_chmap_v3()

JIRA: https://issues.redhat.com/browse/RHEL-118908

commit 89f0add
Author: Dan Carpenter <dan.carpenter@linaro.org>
Date: Mon Aug 18 12:59:45 2025 +0300

    ALSA: usb-audio: Fix size validation in convert_chmap_v3()

    The "p" pointer is void so sizeof(*p) is 1.  The intent was to check
    sizeof(*cs_desc), which is 3, instead.

    Fixes: ecfd411 ("ALSA: usb-audio: Validate UAC3 cluster segment descriptors")
    Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
    Link: https://patch.msgid.link/aKL5kftC1qGt6lpv@stanley.mountain
    Signed-off-by: Takashi Iwai <tiwai@suse.de>

Signed-off-by: Jaroslav Kysela <jkysela@redhat.com>

Author: jkysela-rh

sound/usb/stream.c

@@ -349,7 +349,7 @@ snd_pcm_chmap_elem *convert_chmap_v3(struct uac3_cluster_header_descriptor
 		u16 cs_len;
 		u8 cs_type;
 
-		if (len < sizeof(*p))
+		if (len < sizeof(*cs_desc))
 			break;
 		cs_len = le16_to_cpu(cs_desc->wLength);
 		if (len < cs_len)