Fixed initialization of external prototypes with object entry.

When external was NULL (for example, when .u.object.properties is not
declared), an arithmetic operation was performed with NULL pointer which
is undefined behavior.

Found by UndefinedBehaviorSanitizer.

diff --git a/src/njs_extern.c b/src/njs_extern.c
index 50ac76c4189f7ec3388323ac7927490e3e67b80d..329ed69d59e34945ba4820e7aaa26334143b43f1 100644 (file)
--- a/src/njs_extern.c
+++ b/src/njs_extern.c
@@ -34,6 +34,10 @@ njs_external_add(njs_vm_t *vm, njs_arr_t *protos,
     hash = &slot->external_shared_hash;
     njs_lvlhsh_init(hash);
 
+    if (n == 0) {
+        return NJS_OK;
+    }
+
     lhq.replace = 0;
     lhq.proto = &njs_object_hash_proto;
     lhq.pool = vm->mem_pool;