Thing Shadow: Fix potential overflow of shadow buffer (#124)

Potential overflow occurs if SHADOW_MAX_SIZE_OF_RX_BUFFER is overriden
to less than the default (AWS_IOT_MQTT_RX_BUF_LEN+1).

Author: projectgus

samples/linux/shadow_sample/aws_iot_config.h

@@ -38,7 +38,7 @@
 #define AWS_IOT_MQTT_NUM_SUBSCRIBE_HANDLERS 5 ///< Maximum number of topic filters the MQTT client can handle at any given time. This should be increased appropriately when using Thing Shadow
 
 // Thing Shadow specific configs
-#define SHADOW_MAX_SIZE_OF_RX_BUFFER AWS_IOT_MQTT_RX_BUF_LEN+1 ///< Maximum size of the SHADOW buffer to store the received Shadow message
+#define SHADOW_MAX_SIZE_OF_RX_BUFFER (AWS_IOT_MQTT_RX_BUF_LEN+1) ///< Maximum size of the SHADOW buffer to store the received Shadow message, including terminating NULL byte.
 #define MAX_SIZE_OF_UNIQUE_CLIENT_ID_BYTES 80  ///< Maximum size of the Unique Client Id. For More info on the Client Id refer \ref response "Acknowledgments"
 #define MAX_SIZE_CLIENT_ID_WITH_SEQUENCE MAX_SIZE_OF_UNIQUE_CLIENT_ID_BYTES + 10 ///< This is size of the extra sequence number that will be appended to the Unique client Id
 #define MAX_SIZE_CLIENT_TOKEN_CLIENT_SEQUENCE MAX_SIZE_CLIENT_ID_WITH_SEQUENCE + 20 ///< This is size of the the total clientToken key and value pair in the JSON

samples/linux/shadow_sample_console_echo/aws_iot_config.h

@@ -38,7 +38,7 @@
 #define AWS_IOT_MQTT_NUM_SUBSCRIBE_HANDLERS 5 ///< Maximum number of topic filters the MQTT client can handle at any given time. This should be increased appropriately when using Thing Shadow
 
 // Thing Shadow specific configs
-#define SHADOW_MAX_SIZE_OF_RX_BUFFER AWS_IOT_MQTT_RX_BUF_LEN+1 ///< Maximum size of the SHADOW buffer to store the received Shadow message
+#define SHADOW_MAX_SIZE_OF_RX_BUFFER (AWS_IOT_MQTT_RX_BUF_LEN+1) ///< Maximum size of the SHADOW buffer to store the received Shadow message, including terminating NULL byte.
 #define MAX_SIZE_OF_UNIQUE_CLIENT_ID_BYTES 80  ///< Maximum size of the Unique Client Id. For More info on the Client Id refer \ref response "Acknowledgments"
 #define MAX_SIZE_CLIENT_ID_WITH_SEQUENCE MAX_SIZE_OF_UNIQUE_CLIENT_ID_BYTES + 10 ///< This is size of the extra sequence number that will be appended to the Unique client Id
 #define MAX_SIZE_CLIENT_TOKEN_CLIENT_SEQUENCE MAX_SIZE_CLIENT_ID_WITH_SEQUENCE + 20 ///< This is size of the the total clientToken key and value pair in the JSON

samples/linux/subscribe_publish_cpp_sample/aws_iot_config.h

@@ -38,7 +38,7 @@
 #define AWS_IOT_MQTT_NUM_SUBSCRIBE_HANDLERS 5 ///< Maximum number of topic filters the MQTT client can handle at any given time. This should be increased appropriately when using Thing Shadow
 
 // Thing Shadow specific configs
-#define SHADOW_MAX_SIZE_OF_RX_BUFFER AWS_IOT_MQTT_RX_BUF_LEN+1 ///< Maximum size of the SHADOW buffer to store the received Shadow message
+#define SHADOW_MAX_SIZE_OF_RX_BUFFER (AWS_IOT_MQTT_RX_BUF_LEN+1) ///< Maximum size of the SHADOW buffer to store the received Shadow message, including terminating NULL byte.
 #define MAX_SIZE_OF_UNIQUE_CLIENT_ID_BYTES 80  ///< Maximum size of the Unique Client Id. For More info on the Client Id refer \ref response "Acknowledgments"
 #define MAX_SIZE_CLIENT_ID_WITH_SEQUENCE MAX_SIZE_OF_UNIQUE_CLIENT_ID_BYTES + 10 ///< This is size of the extra sequence number that will be appended to the Unique client Id
 #define MAX_SIZE_CLIENT_TOKEN_CLIENT_SEQUENCE MAX_SIZE_CLIENT_ID_WITH_SEQUENCE + 20 ///< This is size of the the total clientToken key and value pair in the JSON

samples/linux/subscribe_publish_library_sample/aws_iot_config.h

@@ -38,7 +38,7 @@
 #define AWS_IOT_MQTT_NUM_SUBSCRIBE_HANDLERS 5 ///< Maximum number of topic filters the MQTT client can handle at any given time. This should be increased appropriately when using Thing Shadow
 
 // Thing Shadow specific configs
-#define SHADOW_MAX_SIZE_OF_RX_BUFFER AWS_IOT_MQTT_RX_BUF_LEN+1 ///< Maximum size of the SHADOW buffer to store the received Shadow message
+#define SHADOW_MAX_SIZE_OF_RX_BUFFER (AWS_IOT_MQTT_RX_BUF_LEN+1) ///< Maximum size of the SHADOW buffer to store the received Shadow message, including terminating NULL byte.
 #define MAX_SIZE_OF_UNIQUE_CLIENT_ID_BYTES 80  ///< Maximum size of the Unique Client Id. For More info on the Client Id refer \ref response "Acknowledgments"
 #define MAX_SIZE_CLIENT_ID_WITH_SEQUENCE MAX_SIZE_OF_UNIQUE_CLIENT_ID_BYTES + 10 ///< This is size of the extra sequence number that will be appended to the Unique client Id
 #define MAX_SIZE_CLIENT_TOKEN_CLIENT_SEQUENCE MAX_SIZE_CLIENT_ID_WITH_SEQUENCE + 20 ///< This is size of the the total clientToken key and value pair in the JSON

samples/linux/subscribe_publish_sample/aws_iot_config.h

@@ -38,7 +38,7 @@
 #define AWS_IOT_MQTT_NUM_SUBSCRIBE_HANDLERS 5 ///< Maximum number of topic filters the MQTT client can handle at any given time. This should be increased appropriately when using Thing Shadow
 
 // Thing Shadow specific configs
-#define SHADOW_MAX_SIZE_OF_RX_BUFFER AWS_IOT_MQTT_RX_BUF_LEN+1 ///< Maximum size of the SHADOW buffer to store the received Shadow message
+#define SHADOW_MAX_SIZE_OF_RX_BUFFER (AWS_IOT_MQTT_RX_BUF_LEN+1) ///< Maximum size of the SHADOW buffer to store the received Shadow message, including terminating NULL byte.
 #define MAX_SIZE_OF_UNIQUE_CLIENT_ID_BYTES 80  ///< Maximum size of the Unique Client Id. For More info on the Client Id refer \ref response "Acknowledgments"
 #define MAX_SIZE_CLIENT_ID_WITH_SEQUENCE MAX_SIZE_OF_UNIQUE_CLIENT_ID_BYTES + 10 ///< This is size of the extra sequence number that will be appended to the Unique client Id
 #define MAX_SIZE_CLIENT_TOKEN_CLIENT_SEQUENCE MAX_SIZE_CLIENT_ID_WITH_SEQUENCE + 20 ///< This is size of the the total clientToken key and value pair in the JSON

src/aws_iot_shadow_records.c

@@ -188,7 +188,7 @@ static void AckStatusCallback(AWS_IoT_Client *pClient, char *topicName, uint16_t
 	IOT_UNUSED(topicNameLen);
 	IOT_UNUSED(pData);
 
-	if(params->payloadLen > SHADOW_MAX_SIZE_OF_RX_BUFFER) {
+	if(params->payloadLen >= SHADOW_MAX_SIZE_OF_RX_BUFFER) {
 		IOT_WARN("Payload larger than RX Buffer");
 		return;
 	}
@@ -484,7 +484,7 @@ static void shadow_delta_callback(AWS_IoT_Client *pClient, char *topicName,
 	IOT_UNUSED(topicNameLen);
 	IOT_UNUSED(pData);
 
-	if(params->payloadLen > SHADOW_MAX_SIZE_OF_RX_BUFFER) {
+	if(params->payloadLen >= SHADOW_MAX_SIZE_OF_RX_BUFFER) {
 		IOT_WARN("Payload larger than RX Buffer");
 		return;
 	}

tests/integration/include/aws_iot_config.h

@@ -33,7 +33,7 @@
 #define AWS_IOT_MQTT_NUM_SUBSCRIBE_HANDLERS 5	///< Maximum number of topic filters the MQTT client can handle at any given time. This should be increased appropriately when using Thing Shadow
 
 // Thing Shadow specific configs
-#define SHADOW_MAX_SIZE_OF_RX_BUFFER AWS_IOT_MQTT_RX_BUF_LEN+1						///< Maximum size of the SHADOW buffer to store the received Shadow message
+#define SHADOW_MAX_SIZE_OF_RX_BUFFER (AWS_IOT_MQTT_RX_BUF_LEN+1)					///< Maximum size of the SHADOW buffer to store the received Shadow message, including terminating NULL byte.
 #define MAX_SIZE_OF_UNIQUE_CLIENT_ID_BYTES 80										///< Maximum size of the Unique Client Id. For More info on the Client Id refer \ref response "Acknowledgments"
 #define MAX_SIZE_CLIENT_ID_WITH_SEQUENCE MAX_SIZE_OF_UNIQUE_CLIENT_ID_BYTES + 10	///< This is size of the extra sequence number that will be appended to the Unique client Id
 #define MAX_SIZE_CLIENT_TOKEN_CLIENT_SEQUENCE MAX_SIZE_CLIENT_ID_WITH_SEQUENCE + 20	///< This is size of the the total clientToken key and value pair in the JSON