sandbox: vm: make kmalloc(size: 0) return NULL

sandbox/vm/kmalloc.c

@@ -28,6 +28,10 @@ static const size_t nr_size_n_caches = sizeof size_n_caches / sizeof size_n_cach
 
 void *kmalloc(size_t count, vm_flags_t flags)
 {
+	if (!count) {
+		return NULL;
+	}
+
 	vm_cache_t *best_fit = NULL;
 	for (size_t i = 0; i < nr_size_n_caches; i++) {
 		if (size_n_caches[i].c_obj_size >= count) {
@@ -43,7 +47,7 @@ void *kmalloc(size_t count, vm_flags_t flags)
 	if (!VM_CACHE_INITIALISED(best_fit)) {
 		vm_cache_init(best_fit);
 	}
-	
+
 	return vm_cache_alloc(best_fit, flags);
 }