ALSA: allocation may fail in snd_pcm_oss_change_params()

Allocation may fail, show if it did.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
[Additional fix for invalid runtime->oss.prepare flag set by tiwai]
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/oss/pcm_oss.c

@@ -1043,10 +1043,15 @@ static int snd_pcm_oss_change_params(struct snd_pcm_substream *substream)
 	runtime->oss.channels = params_channels(params);
 	runtime->oss.rate = params_rate(params);
 
-	runtime->oss.params = 0;
-	runtime->oss.prepare = 1;
 	vfree(runtime->oss.buffer);
 	runtime->oss.buffer = vmalloc(runtime->oss.period_bytes);
+	if (!runtime->oss.buffer) {
+		err = -ENOMEM;
+		goto failure;
+	}
+
+	runtime->oss.params = 0;
+	runtime->oss.prepare = 1;
 	runtime->oss.buffer_used = 0;
 	if (runtime->dma_area)
 		snd_pcm_format_set_silence(runtime->format, runtime->dma_area, bytes_to_samples(runtime, runtime->dma_bytes));