Fix possible integer overflow (#836)

* Fix possible integer overflow

---------

Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>

portable/Common/mpu_wrappers_v2.c

@@ -112,6 +112,16 @@
  */
     #define CONVERT_TO_INTERNAL_INDEX( lIndex )    ( ( lIndex ) - INDEX_OFFSET )
 
+/**
+ * @brief Max value that fits in a size_t type.
+ */
+    #define mpuSIZE_MAX    ( ~( ( size_t ) 0 ) )
+
+/**
+ * @brief Check if multiplying a and b will result in overflow.
+ */
+    #define mpuMULTIPLY_WILL_OVERFLOW( a, b )    ( ( ( a ) > 0 ) && ( ( b ) > ( mpuSIZE_MAX / ( a ) ) ) )
+
 /**
  * @brief Get the index of a free slot in the kernel object pool.
  *
@@ -1035,10 +1045,12 @@
                                                   UBaseType_t uxArraySize,
                                                   configRUN_TIME_COUNTER_TYPE * pulTotalRunTime ) /* PRIVILEGED_FUNCTION */
         {
-            UBaseType_t uxReturn = pdFALSE;
+            UBaseType_t uxReturn = 0;
             UBaseType_t xIsTaskStatusArrayWriteable = pdFALSE;
             UBaseType_t xIsTotalRunTimeWriteable = pdFALSE;
 
+            if( mpuMULTIPLY_WILL_OVERFLOW( sizeof( TaskStatus_t ), uxArraySize ) == 0 )
+            {
                 xIsTaskStatusArrayWriteable = xPortIsAuthorizedToAccessBuffer( pxTaskStatusArray,
                                                                                sizeof( TaskStatus_t ) * uxArraySize,
                                                                                tskMPU_WRITE_PERMISSION );
@@ -1055,6 +1067,7 @@
                 {
                     uxReturn = uxTaskGetSystemState( pxTaskStatusArray, uxArraySize, pulTotalRunTime );
                 }
+            }
 
             return uxReturn;
         }