ASoC: SOF: Intel: cnl: Do not process IPC reply before firmware boot

It is not yet clear, but it is possible to create a firmware so broken
that it will send a reply message before a FW_READY message (it is not
yet clear if FW_READY will arrive later).
Since the reply_data is allocated only after the FW_READY message, this
will lead to a NULL pointer dereference if not filtered out.

The issue was reported with IPC4 firmware but the same condition is present
for IPC3.
Reported-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20220712122357.31282-2-peter.ujfalusi@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/intel/cnl.c

@@ -60,17 +60,23 @@ irqreturn_t cnl_ipc4_irq_thread(int irq, void *context)
 
 		if (primary & SOF_IPC4_MSG_DIR_MASK) {
 			/* Reply received */
-			struct sof_ipc4_msg *data = sdev->ipc->msg.reply_data;
+			if (likely(sdev->fw_state == SOF_FW_BOOT_COMPLETE)) {
+				struct sof_ipc4_msg *data = sdev->ipc->msg.reply_data;
 
-			data->primary = primary;
-			data->extension = extension;
+				data->primary = primary;
+				data->extension = extension;
 
-			spin_lock_irq(&sdev->ipc_lock);
+				spin_lock_irq(&sdev->ipc_lock);
 
-			snd_sof_ipc_get_reply(sdev);
-			snd_sof_ipc_reply(sdev, data->primary);
+				snd_sof_ipc_get_reply(sdev);
+				snd_sof_ipc_reply(sdev, data->primary);
 
-			spin_unlock_irq(&sdev->ipc_lock);
+				spin_unlock_irq(&sdev->ipc_lock);
+			} else {
+				dev_dbg_ratelimited(sdev->dev,
+						    "IPC reply before FW_READY: %#x|%#x\n",
+						    primary, extension);
+			}
 		} else {
 			/* Notification received */
 			notification_data.primary = primary;
@@ -124,15 +130,20 @@ irqreturn_t cnl_ipc_irq_thread(int irq, void *context)
 					CNL_DSP_REG_HIPCCTL,
 					CNL_DSP_REG_HIPCCTL_DONE, 0);
 
-		spin_lock_irq(&sdev->ipc_lock);
+		if (likely(sdev->fw_state == SOF_FW_BOOT_COMPLETE)) {
+			spin_lock_irq(&sdev->ipc_lock);
 
-		/* handle immediate reply from DSP core */
-		hda_dsp_ipc_get_reply(sdev);
-		snd_sof_ipc_reply(sdev, msg);
+			/* handle immediate reply from DSP core */
+			hda_dsp_ipc_get_reply(sdev);
+			snd_sof_ipc_reply(sdev, msg);
 
-		cnl_ipc_dsp_done(sdev);
+			cnl_ipc_dsp_done(sdev);
 
-		spin_unlock_irq(&sdev->ipc_lock);
+			spin_unlock_irq(&sdev->ipc_lock);
+		} else {
+			dev_dbg_ratelimited(sdev->dev, "IPC reply before FW_READY: %#x\n",
+					    msg);
+		}
 
 		ipc_irq = true;
 	}