ALSA: hda: Error out if invalid stream is being setup

Scenario when snd_hdac_stream_setup_periods() receives an instance of
struct hdac_stream with neither ->substream nor ->cstream initialized is
invalid.

Simultaneously addresses "uninitialized symbol 'dmab'" error reported by
Smatch.

Fixes: 3e95822 ("ALSA: hda: Interrupt servicing and BDL setup for compress streams")
Signed-off-by: Cezary Rojewski <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Takashi Iwai <[email protected]>

Author: crojewsk-intel

sound/hda/hdac_stream.c

@@ -500,6 +500,9 @@ int snd_hdac_stream_setup_periods(struct hdac_stream *azx_dev)
 		dmab = snd_pcm_get_dma_buf(substream);
 	} else if (cstream) {
 		dmab = snd_pcm_get_dma_buf(cstream);
+	} else {
+		WARN(1, "No substream or cstream assigned\n");
+		return -EINVAL;
 	}
 
 	/* reset BDL address */