ALSA: usb-audio: Fix out-of-bounds read in snd_usb_get_audioformat_uac3()

ALSA: usb-audio: Fix out-of-bounds read in snd_usb_get_audioformat_uac3()

In snd_usb_get_audioformat_uac3(), the length value returned from
snd_usb_ctl_msg() is used directly for memory allocation without
validation. This length is controlled by the USB device.

The allocated buffer is cast to a uac3_cluster_header_descriptor
and its fields are accessed without verifying that the buffer
is large enough. If the device returns a smaller than expected
length, this leads to an out-of-bounds read.

Add a length check to ensure the buffer is large enough for
uac3_cluster_header_descriptor.

Signed-off-by: Youngjun Lee <yjjuny.lee@samsung.com>
Fixes: 9a2fe9b801f5 ("ALSA: usb: initial USB Audio Device Class 3.0 support")
Link: https://patch.msgid.link/20250623-uac3-oob-fix-v1-1-527303eaf40a@samsung.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>