ASoC: SOF: imx: imx8m: Bar index is only valid for IRAM and SRAM types

i.MX8 only uses SOF_FW_BLK_TYPE_IRAM (1) and SOF_FW_BLK_TYPE_SRAM (3)
bars, everything else is left as 0 in sdev->bar[] array.

If a broken or purposefully crafted firmware image is loaded with other
types of FW_BLK_TYPE then a kernel crash can be triggered.

Make sure that only IRAM/SRAM type is converted to bar index.

Fixes: afb93d7 ("ASoC: SOF: imx: Add i.MX8M HW support")
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Daniel Baluta <daniel.baluta@gmail.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Link: https://lore.kernel.org/r/20210915122116.18317-6-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/imx/imx8m.c

@@ -228,7 +228,14 @@ static int imx8m_remove(struct snd_sof_dev *sdev)
 /* on i.MX8 there is 1 to 1 match between type and BAR idx */
 static int imx8m_get_bar_index(struct snd_sof_dev *sdev, u32 type)
 {
-	return type;
+	/* Only IRAM and SRAM bars are valid */
+	switch (type) {
+	case SOF_FW_BLK_TYPE_IRAM:
+	case SOF_FW_BLK_TYPE_SRAM:
+		return type;
+	default:
+		return -EINVAL;
+	}
 }
 
 static void imx8m_ipc_msg_data(struct snd_sof_dev *sdev,