Add addition overflow check for stream buffer (#226)

Author: cobusve

stream_buffer.c

@@ -258,8 +258,16 @@ static void prvInitialiseNewStreamBuffer( StreamBuffer_t * const pxStreamBuffer,
          * this is a quirk of the implementation that means otherwise the free
          * space would be reported as one byte smaller than would be logically
          * expected. */
-        xBufferSizeBytes++;
-        pucAllocatedMemory = ( uint8_t * ) pvPortMalloc( xBufferSizeBytes + sizeof( StreamBuffer_t ) ); /*lint !e9079 malloc() only returns void*. */
+        if( xBufferSizeBytes < ( xBufferSizeBytes + 1 + sizeof( StreamBuffer_t ) ) )
+        {
+            xBufferSizeBytes++;
+            pucAllocatedMemory = ( uint8_t * ) pvPortMalloc( xBufferSizeBytes + sizeof( StreamBuffer_t ) ); /*lint !e9079 malloc() only returns void*. */
+        }
+        else
+        {
+            pucAllocatedMemory = NULL;
+        }
+        
 
         if( pucAllocatedMemory != NULL )
         {