ALSA: wavefront: Proper check of get_user() error

The antient ISA wavefront driver reads its sample patch data (uploaded
over an ioctl) via __get_user() with no good reason; likely just for
some performance optimizations in the past.  Let's change this to the
standard get_user() and the error check for handling the fault case
properly.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220510103626.16635-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/isa/wavefront/wavefront_synth.c

@@ -1094,7 +1094,8 @@ wavefront_send_sample (snd_wavefront_t *dev,
 
 			if (dataptr < data_end) {
 		
-				__get_user (sample_short, dataptr);
+				if (get_user(sample_short, dataptr))
+					return -EFAULT;
 				dataptr += skip;
 		
 				if (data_is_unsigned) { /* GUS ? */