[修改] 增加freeRTOS

1. 版本FreeRTOSv202212.01，命名为kernel；

kernel/FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP/test/cbmc/proofs/utility/memory_assignments.c

@@ -0,0 +1,32 @@
+#include <stdlib.h>
+
+#define ensure_memory_is_valid( px, length )    ( px != NULL ) && __CPROVER_w_ok( ( px ), length )
+
+/* Implementation of safe malloc which returns NULL if the requested size is 0.
+ * Warning: The behavior of malloc(0) is platform dependent.
+ * It is possible for malloc(0) to return an address without allocating memory.*/
+void * safeMalloc( size_t xWantedSize )
+{
+    return nondet_bool() ? malloc( xWantedSize ) : NULL;
+}
+
+/* Memory assignment for FreeRTOS_Socket_t */
+FreeRTOS_Socket_t * ensure_FreeRTOS_Socket_t_is_allocated()
+{
+    FreeRTOS_Socket_t * pxSocket = safeMalloc( sizeof( FreeRTOS_Socket_t ) );
+
+    if( ensure_memory_is_valid( pxSocket, sizeof( FreeRTOS_Socket_t ) ) )
+    {
+        pxSocket->u.xTCP.rxStream = safeMalloc( sizeof( StreamBuffer_t ) );
+        pxSocket->u.xTCP.txStream = safeMalloc( sizeof( StreamBuffer_t ) );
+        pxSocket->u.xTCP.pxPeerSocket = safeMalloc( sizeof( FreeRTOS_Socket_t ) );
+    }
+
+    return pxSocket;
+}
+
+/* Memory assignment for FreeRTOS_Network_Buffer */
+NetworkBufferDescriptor_t * ensure_FreeRTOS_NetworkBuffer_is_allocated()
+{
+    return safeMalloc( sizeof( NetworkBufferDescriptor_t ) );
+}