heap: Add integer overflow checks

components/heap/multi_heap_poisoning.c

@@ -175,6 +175,9 @@ static bool verify_fill_pattern(void *data, size_t size, bool print_errors, bool
 
 void *multi_heap_malloc(multi_heap_handle_t heap, size_t size)
 {
+    if(size > SIZE_MAX - POISON_OVERHEAD) {
+        return NULL;
+    }
     multi_heap_internal_lock(heap);
     poison_head_t *head = multi_heap_malloc_impl(heap, size + POISON_OVERHEAD);
     uint8_t *data = NULL;
@@ -216,6 +219,9 @@ void *multi_heap_realloc(multi_heap_handle_t heap, void *p, size_t size)
     poison_head_t *new_head;
     void *result = NULL;
 
+    if(size > SIZE_MAX - POISON_OVERHEAD) {
+        return NULL;
+    }
     if (p == NULL) {
         return multi_heap_malloc(heap, size);
     }