ASoC: SOF: stream-ipc: Check for cstream nullity in sof_ipc_msg_data()

The nullity of sps->cstream should be checked similarly as it is done in
sof_set_stream_data_offset() function.
Assuming that it is not NULL if sps->stream is NULL is incorrect and can
lead to NULL pointer dereference.

Fixes: ef8ba9f ("ASoC: SOF: Add support for compress API for stream data/offset")
Cc: stable@vger.kernel.org
Reported-by: Curtis Malainey <cujomalainey@chromium.org>
Closes: #5214
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>

Author: ujfalusi

sound/soc/sof/stream-ipc.c

@@ -43,14 +43,18 @@ int sof_ipc_msg_data(struct snd_sof_dev *sdev,
 				return -ESTRPIPE;
 
 			posn_offset = stream->posn_offset;
-		} else {
+		} else if (sps->cstream) {
 
 			struct sof_compr_stream *sstream = sps->cstream->runtime->private_data;
 
 			if (!sstream)
 				return -ESTRPIPE;
 
 			posn_offset = sstream->posn_offset;
+
+		} else {
+			dev_err(sdev->dev, "%s: No stream opened\n", __func__);
+			return -EINVAL;
 		}
 
 		snd_sof_dsp_mailbox_read(sdev, posn_offset, p, sz);