dsp: q6usm: Check size of payload before access

Check size of payload before access in q6usm_mmapcallback.

Change-Id: Iff0672532c2ea40e7129237a92d8365d6b554cf2
Signed-off-by: Vatsal Bucha <[email protected]>

dsp/q6usm.c

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Copyright (c) 2012-2018, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2012-2019, The Linux Foundation. All rights reserved.
  */
 #include <linux/mutex.h>
 #include <linux/wait.h>
@@ -490,6 +490,11 @@ static int32_t q6usm_mmapcallback(struct apr_client_data *data, void *priv)
 	uint32_t token;
 	uint32_t *payload = data->payload;
 
+	if (data->payload_size < (2 * sizeof(uint32_t))) {
+		pr_err("%s: payload has invalid size[%d]\n", __func__,
+		       data->payload_size);
+		return -EINVAL;
+	}
 	pr_debug("%s: ptr0[0x%x]; ptr1[0x%x]; opcode[0x%x]\n",
 		 __func__, payload[0], payload[1], data->opcode);
 	pr_debug("%s: token[0x%x]; payload_size[%d]; src[%d]; dest[%d];\n",