Merge branch 'PHP-7.4'

* PHP-7.4:
  Fix #79149: SEGV in mb_convert_encoding with non-string encodings

Author: cmb69

ext/mbstring/mbstring.c

@@ -2879,12 +2879,12 @@ PHP_FUNCTION(mb_convert_encoding)
 
 					if ( _from_encodings) {
 						l = strlen(_from_encodings);
-						n = strlen(Z_STRVAL_P(hash_entry));
+						n = strlen(ZSTR_VAL(encoding_str));
 						_from_encodings = erealloc(_from_encodings, l+n+2);
 						memcpy(_from_encodings + l, ",", 1);
-						memcpy(_from_encodings + l + 1, Z_STRVAL_P(hash_entry), Z_STRLEN_P(hash_entry) + 1);
+						memcpy(_from_encodings + l + 1, ZSTR_VAL(encoding_str), ZSTR_LEN(encoding_str) + 1);
 					} else {
-						_from_encodings = estrdup(Z_STRVAL_P(hash_entry));
+						_from_encodings = estrdup(ZSTR_VAL(encoding_str));
 					}
 					zend_string_release(encoding_str);
 				} ZEND_HASH_FOREACH_END();

ext/mbstring/tests/bug79149.phpt

@@ -0,0 +1,21 @@
+--TEST--
+Bug #79149 (SEGV in mb_convert_encoding with non-string encodings)
+--SKIPIF--
+<?php
+if (!extension_loaded('mbstring')) die('skip mbstring extension not available');
+?>
+--FILE--
+<?php
+var_dump(mb_convert_encoding("", "UTF-8", [0]));
+var_dump(mb_convert_encoding('foo', 'UTF-8', array(['bar'], ['baz'])));
+?>
+--EXPECTF--
+Warning: mb_convert_encoding(): Illegal character encoding specified in %s on line %d
+string(0) ""
+
+Notice: Array to string conversion in %s on line %d
+
+Notice: Array to string conversion in %s on line %d
+
+Warning: mb_convert_encoding(): Illegal character encoding specified in %s on line %d
+string(3) "foo"