Fixed bug #79930

We're inserting src_zval, so that's what we should addref.

Author: nikic

NEWS

@@ -17,6 +17,10 @@ PHP                                                                        NEWS
   . Fixed bug #73060 (php failed with error after temp folder cleaned up).
     (cmb)
 
+- Standard:
+  . Fixed bug #79930 (array_merge_recursive() crashes when called with array
+    with single reference). (Nikita)
+
 06 Aug 2020, PHP 7.3.21
 
 - Apache:

ext/standard/array.c

@@ -3615,7 +3615,7 @@ PHPAPI int php_array_merge_recursive(HashTable *dest, HashTable *src) /* {{{ */
 						return 0;
 					}
 				} else {
-					Z_TRY_ADDREF_P(src_entry);
+					Z_TRY_ADDREF_P(src_zval);
 					zend_hash_next_index_insert(Z_ARRVAL_P(dest_zval), src_zval);
 				}
 				zval_ptr_dtor(&tmp);

ext/standard/tests/array/bug79930.phpt

@@ -0,0 +1,33 @@
+--TEST--
+Bug #79930: array_merge_recursive() crashes when called with array with single reference
+--FILE--
+<?php
+
+$a = 'a';
+$array = [
+    'value' => $a . 'b',
+];
+
+// Create rc=1 reference.
+array_walk($array, function () {});
+
+$m = array_merge_recursive(['value' => 'a'], $array);
+
+var_dump($a, $array, $m);
+
+?>
+--EXPECT--
+string(1) "a"
+array(1) {
+  ["value"]=>
+  string(2) "ab"
+}
+array(1) {
+  ["value"]=>
+  array(2) {
+    [0]=>
+    string(1) "a"
+    [1]=>
+    string(2) "ab"
+  }
+}