Add heap protector to allocted heap blocks (FreeRTOS#1125)

When validate those allocated heap block structure, the canary is not used.
Do xor with canary when allocating a new block.

Signed-off-by: wangfei_chen <wangfei_chen@realsil.com.cn>
Co-authored-by: wangfei_chen <wangfei_chen@realsil.com.cn>

Author: Saiiijchan

portable/MemMang/heap_4.c

@@ -308,7 +308,7 @@ void * pvPortMalloc( size_t xWantedSize )
                     /* The block is being returned - it is allocated and owned
                      * by the application and has no "next" block. */
                     heapALLOCATE_BLOCK( pxBlock );
-                    pxBlock->pxNextFreeBlock = NULL;
+                    pxBlock->pxNextFreeBlock = heapPROTECT_BLOCK_POINTER( NULL );
                     xNumberOfSuccessfulAllocations++;
                 }
                 else
@@ -367,11 +367,11 @@ void vPortFree( void * pv )
 
         heapVALIDATE_BLOCK_POINTER( pxLink );
         configASSERT( heapBLOCK_IS_ALLOCATED( pxLink ) != 0 );
-        configASSERT( pxLink->pxNextFreeBlock == NULL );
+        configASSERT( pxLink->pxNextFreeBlock == heapPROTECT_BLOCK_POINTER( NULL ) );
 
         if( heapBLOCK_IS_ALLOCATED( pxLink ) != 0 )
         {
-            if( pxLink->pxNextFreeBlock == NULL )
+            if( pxLink->pxNextFreeBlock == heapPROTECT_BLOCK_POINTER( NULL ) )
             {
                 /* The block is being returned to the heap - it is no longer
                  * allocated. */

portable/MemMang/heap_5.c

@@ -336,7 +336,7 @@ void * pvPortMalloc( size_t xWantedSize )
                     /* The block is being returned - it is allocated and owned
                      * by the application and has no "next" block. */
                     heapALLOCATE_BLOCK( pxBlock );
-                    pxBlock->pxNextFreeBlock = NULL;
+                    pxBlock->pxNextFreeBlock = heapPROTECT_BLOCK_POINTER( NULL );
                     xNumberOfSuccessfulAllocations++;
                 }
                 else
@@ -395,11 +395,11 @@ void vPortFree( void * pv )
 
         heapVALIDATE_BLOCK_POINTER( pxLink );
         configASSERT( heapBLOCK_IS_ALLOCATED( pxLink ) != 0 );
-        configASSERT( pxLink->pxNextFreeBlock == NULL );
+        configASSERT( pxLink->pxNextFreeBlock == heapPROTECT_BLOCK_POINTER( NULL ) );
 
         if( heapBLOCK_IS_ALLOCATED( pxLink ) != 0 )
         {
-            if( pxLink->pxNextFreeBlock == NULL )
+            if( pxLink->pxNextFreeBlock == heapPROTECT_BLOCK_POINTER( NULL ) )
             {
                 /* The block is being returned to the heap - it is no longer
                  * allocated. */