CVE-2026-43279: ALSA: usb-audio: Add sanity check for OOB writes at silencing

In the Linux kernel, the following vulnerability has been resolved:

ALSA: usb-audio: Add sanity check for OOB writes at silencing

At silencing the playback URB packets in the implicit fb mode before the actual playback, we blindly assume that the received packets fit with the buffer size. But when the setup in the capture stream differs from the playback stream (e.g. due to the USB core limitation of max packet size), such an inconsistency may lead to OOB writes to the buffer, resulting in a crash.

For addressing it, add a sanity check of the transfer buffer size at preparesilenturb(), and stop the data copy if the received data overflows. Also, report back the transfer error properly from there, too.

Note that this doesn't fix the root cause of the playback error itself, but this merely covers the kernel Oops.