Fix bug #70172 - Use After Free Vulnerability in unserialize()

4 files changed, 121 insertions, 42 deletions

diff --git a/ext/standard/tests/serialize/bug70172.phpt b/ext/standard/tests/serialize/bug70172.phpt
new file mode 100644
index 0000000000..0e9d7ed89a
--- /dev/null
+++ b/ext/standard/tests/serialize/bug70172.phpt
@@ -0,0 +1,52 @@
+--TEST--
+Bug #70172 - Use After Free Vulnerability in unserialize()
+--FILE--
+<?php
+class obj implements Serializable {
+	var $data;
+	function serialize() {
+		return serialize($this->data);
+	}
+	function unserialize($data) {
+		$this->data = unserialize($data);
+	}
+}
+
+$fakezval = ptr2str(1122334455);
+$fakezval .= ptr2str(0);
+$fakezval .= "\x00\x00\x00\x00";
+$fakezval .= "\x01";
+$fakezval .= "\x00";
+$fakezval .= "\x00\x00";
+
+$inner = 'r:2;';
+$exploit = 'a:2:{i:0;i:1;i:1;C:3:"obj":'.strlen($inner).':{'.$inner.'}}';
+
+$data = unserialize($exploit);
+
+for ($i = 0; $i < 5; $i++) {
+	$v[$i] = $fakezval.$i;
+}
+
+var_dump($data);
+
+function ptr2str($ptr)
+{
+	$out = '';
+	for ($i = 0; $i < 8; $i++) {
+		$out .= chr($ptr & 0xff);
+		$ptr >>= 8;
+	}
+	return $out;
+}
+?>
+--EXPECTF--
+array(2) {
+  [0]=>
+  int(1)
+  [1]=>
+  object(obj)#%d (1) {
+    ["data"]=>
+    int(1)
+  }
+}
\ No newline at end of file
diff --git a/ext/standard/var.c b/ext/standard/var.c
index 7603ff2ee0..33b976f42d 100644
--- a/ext/standard/var.c
+++ b/ext/standard/var.c
@@ -373,7 +373,7 @@ static int php_array_element_export(zval **zv TSRMLS_DC, int num_args, va_list a
 
 	smart_str_appendc(buf, ',');
 	smart_str_appendc(buf, '\n');
-	
+
 	return 0;
 }
 /* }}} */
@@ -392,7 +392,7 @@ static int php_object_element_export(zval **zv TSRMLS_DC, int num_args, va_list
 		const char *pname;
 		char *pname_esc;
 		int  pname_esc_len;
-		
+
 		zend_unmangle_property_name(hash_key->arKey, hash_key->nKeyLength - 1,
 				&class_name, &pname);
 		pname_esc = php_addcslashes(pname, strlen(pname), &pname_esc_len, 0,
@@ -469,7 +469,7 @@ PHPAPI void php_var_export_ex(zval **struc, int level, smart_str *buf TSRMLS_DC)
 			buffer_append_spaces(buf, level - 1);
 		}
 		smart_str_appendc(buf, ')');
-    
+
 		break;
 
 	case IS_OBJECT:
@@ -802,7 +802,7 @@ static void php_var_serialize_intern(smart_str *buf, zval *struc, HashTable *var
 					BG(serialize_lock)++;
 					res = call_user_function_ex(CG(function_table), &struc, &fname, &retval_ptr, 0, 0, 1, NULL TSRMLS_CC);
 					BG(serialize_lock)--;
-                    
+
 					if (EG(exception)) {
 						if (retval_ptr) {
 							zval_ptr_dtor(&retval_ptr);
@@ -951,6 +951,8 @@ PHP_FUNCTION(unserialize)
 	int buf_len;
 	const unsigned char *p;
 	php_unserialize_data_t var_hash;
+	int oldlevel;
+	zval *old_rval = return_value;
 
 	if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s", &buf, &buf_len) == FAILURE) {
 		RETURN_FALSE;
@@ -970,6 +972,19 @@ PHP_FUNCTION(unserialize)
 		}
 		RETURN_FALSE;
 	}
+	if (return_value != old_rval) {
+		/*
+		 * Terrible hack due to the fact that executor passes us zval *,
+		 * but unserialize with r/R wants to replace it with another zval *
+		 */
+		zval_dtor(old_rval);
+		*old_rval = *return_value;
+		zval_copy_ctor(old_rval);
+		var_push_dtor_no_addref(&var_hash, &return_value);
+		var_push_dtor_no_addref(&var_hash, &old_rval);
+	} else {
+		var_push_dtor(&var_hash, &return_value);
+	}
 	PHP_VAR_UNSERIALIZE_DESTROY(var_hash);
 }
 /* }}} */
diff --git a/ext/standard/var_unserializer.c b/ext/standard/var_unserializer.c
index ffaf680c51..5f2336ec14 100644
--- a/ext/standard/var_unserializer.c
+++ b/ext/standard/var_unserializer.c
@@ -1,4 +1,4 @@
-/* Generated by re2c 0.13.7.5 on Sun Aug 23 19:50:03 2015 */
+/* Generated by re2c 0.13.7.5 on Mon Aug 31 23:15:46 2015 */
 #line 1 "ext/standard/var_unserializer.re"
 /*
   +----------------------------------------------------------------------+
@@ -69,7 +69,7 @@ PHPAPI void var_push_dtor(php_unserialize_data_t *var_hashx, zval **rval)
 
 	var_hash = (*var_hashx)->last_dtor;
 #if VAR_ENTRIES_DBG
-	fprintf(stderr, "var_push_dtor(%ld): %d\n", var_hash?var_hash->used_slots:-1L, Z_TYPE_PP(rval));
+	fprintf(stderr, "var_push_dtor(%p, %ld): %d\n", *rval, var_hash?var_hash->used_slots:-1L, Z_TYPE_PP(rval));
 #endif
 
 	if (!var_hash || var_hash->used_slots == VAR_ENTRIES_MAX) {
@@ -100,7 +100,7 @@ PHPAPI void var_push_dtor_no_addref(php_unserialize_data_t *var_hashx, zval **rv
 
     var_hash = (*var_hashx)->last_dtor;
 #if VAR_ENTRIES_DBG
-	fprintf(stderr, "var_push_dtor_no_addref(%ld): %d (%d)\n", var_hash?var_hash->used_slots:-1L, Z_TYPE_PP(rval), Z_REFCOUNT_PP(rval));
+	fprintf(stderr, "var_push_dtor_no_addref(%p, %ld): %d (%d)\n", *rval, var_hash?var_hash->used_slots:-1L, Z_TYPE_PP(rval), Z_REFCOUNT_PP(rval));
 #endif
 
 	if (!var_hash || var_hash->used_slots == VAR_ENTRIES_MAX) {
@@ -179,6 +179,9 @@ PHPAPI void var_destroy(php_unserialize_data_t *var_hashx)
 
 	while (var_hash) {
 		for (i = 0; i < var_hash->used_slots; i++) {
+#if VAR_ENTRIES_DBG
+    fprintf(stderr, "var_destroy dtor(%p, %ld)\n", var_hash->data[i], Z_REFCOUNT_P(var_hash->data[i]));
+#endif
 			zval_ptr_dtor(&var_hash->data[i]);
 		}
 		next = var_hash->next;
@@ -239,7 +242,7 @@ static char *unserialize_str(const unsigned char **p, size_t *len, size_t maxlen
 #define YYMARKER marker
 
 
-#line 247 "ext/standard/var_unserializer.re"
+#line 250 "ext/standard/var_unserializer.re"
 
 
 
@@ -484,7 +487,7 @@ PHPAPI int php_var_unserialize(UNSERIALIZE_PARAMETER)
 
 
 
-#line 488 "ext/standard/var_unserializer.c"
+#line 491 "ext/standard/var_unserializer.c"
 {
 	YYCTYPE yych;
 	static const unsigned char yybm[] = {
@@ -544,9 +547,9 @@ yy2:
 	yych = *(YYMARKER = ++YYCURSOR);
 	if (yych == ':') goto yy95;
 yy3:
-#line 839 "ext/standard/var_unserializer.re"
+#line 845 "ext/standard/var_unserializer.re"
 	{ return 0; }
-#line 550 "ext/standard/var_unserializer.c"
+#line 553 "ext/standard/var_unserializer.c"
 yy4:
 	yych = *(YYMARKER = ++YYCURSOR);
 	if (yych == ':') goto yy89;
@@ -589,13 +592,13 @@ yy13:
 	goto yy3;
 yy14:
 	++YYCURSOR;
-#line 833 "ext/standard/var_unserializer.re"
+#line 839 "ext/standard/var_unserializer.re"
 	{
 	/* this is the case where we have less data than planned */
 	php_error_docref(NULL TSRMLS_CC, E_NOTICE, "Unexpected end of serialized data");
 	return 0; /* not sure if it should be 0 or 1 here? */
 }
-#line 599 "ext/standard/var_unserializer.c"
+#line 602 "ext/standard/var_unserializer.c"
 yy16:
 	yych = *++YYCURSOR;
 	goto yy3;
@@ -626,7 +629,7 @@ yy20:
 	yych = *++YYCURSOR;
 	if (yych != '"') goto yy18;
 	++YYCURSOR;
-#line 687 "ext/standard/var_unserializer.re"
+#line 692 "ext/standard/var_unserializer.re"
 	{
 	size_t len, len2, len3, maxlen;
 	long elements;
@@ -642,6 +645,7 @@ yy20:
 	zval **args[1];
 	zval *arg_func_name;
 
+    if (!var_hash) return 0;
 	if (*start == 'C') {
 		custom_object = 1;
 	}
@@ -772,7 +776,7 @@ yy20:
 
 	return object_common2(UNSERIALIZE_PASSTHRU, elements);
 }
-#line 776 "ext/standard/var_unserializer.c"
+#line 780 "ext/standard/var_unserializer.c"
 yy25:
 	yych = *++YYCURSOR;
 	if (yych <= ',') {
@@ -797,15 +801,16 @@ yy27:
 	yych = *++YYCURSOR;
 	if (yych != '"') goto yy18;
 	++YYCURSOR;
-#line 679 "ext/standard/var_unserializer.re"
+#line 683 "ext/standard/var_unserializer.re"
 	{
+    if (!var_hash) return 0;
 
 	INIT_PZVAL(*rval);
 
 	return object_common2(UNSERIALIZE_PASSTHRU,
 			object_common1(UNSERIALIZE_PASSTHRU, ZEND_STANDARD_CLASS_DEF_PTR));
 }
-#line 809 "ext/standard/var_unserializer.c"
+#line 814 "ext/standard/var_unserializer.c"
 yy32:
 	yych = *++YYCURSOR;
 	if (yych == '+') goto yy33;
@@ -826,11 +831,12 @@ yy34:
 	yych = *++YYCURSOR;
 	if (yych != '{') goto yy18;
 	++YYCURSOR;
-#line 659 "ext/standard/var_unserializer.re"
+#line 662 "ext/standard/var_unserializer.re"
 	{
 	long elements = parse_iv(start + 2);
 	/* use iv() not uiv() in order to check data range */
 	*p = YYCURSOR;
+    if (!var_hash) return 0;
 
 	if (elements < 0) {
 		return 0;
@@ -846,7 +852,7 @@ yy34:
 
 	return finish_nested_data(UNSERIALIZE_PASSTHRU);
 }
-#line 850 "ext/standard/var_unserializer.c"
+#line 856 "ext/standard/var_unserializer.c"
 yy39:
 	yych = *++YYCURSOR;
 	if (yych == '+') goto yy40;
@@ -867,7 +873,7 @@ yy41:
 	yych = *++YYCURSOR;
 	if (yych != '"') goto yy18;
 	++YYCURSOR;
-#line 630 "ext/standard/var_unserializer.re"
+#line 633 "ext/standard/var_unserializer.re"
 	{
 	size_t len, maxlen;
 	char *str;
@@ -896,7 +902,7 @@ yy41:
 	ZVAL_STRINGL(*rval, str, len, 0);
 	return 1;
 }
-#line 900 "ext/standard/var_unserializer.c"
+#line 906 "ext/standard/var_unserializer.c"
 yy46:
 	yych = *++YYCURSOR;
 	if (yych == '+') goto yy47;
@@ -917,7 +923,7 @@ yy48:
 	yych = *++YYCURSOR;
 	if (yych != '"') goto yy18;
 	++YYCURSOR;
-#line 602 "ext/standard/var_unserializer.re"
+#line 605 "ext/standard/var_unserializer.re"
 	{
 	size_t len, maxlen;
 	char *str;
@@ -945,7 +951,7 @@ yy48:
 	ZVAL_STRINGL(*rval, str, len, 1);
 	return 1;
 }
-#line 949 "ext/standard/var_unserializer.c"
+#line 955 "ext/standard/var_unserializer.c"
 yy53:
 	yych = *++YYCURSOR;
 	if (yych <= '/') {
@@ -1033,7 +1039,7 @@ yy61:
 	}
 yy63:
 	++YYCURSOR;
-#line 592 "ext/standard/var_unserializer.re"
+#line 595 "ext/standard/var_unserializer.re"
 	{
 #if SIZEOF_LONG == 4
 use_double:
@@ -1043,7 +1049,7 @@ use_double:
 	ZVAL_DOUBLE(*rval, zend_strtod((const char *)start + 2, NULL));
 	return 1;
 }
-#line 1047 "ext/standard/var_unserializer.c"
+#line 1053 "ext/standard/var_unserializer.c"
 yy65:
 	yych = *++YYCURSOR;
 	if (yych <= ',') {
@@ -1102,7 +1108,7 @@ yy73:
 	yych = *++YYCURSOR;
 	if (yych != ';') goto yy18;
 	++YYCURSOR;
-#line 577 "ext/standard/var_unserializer.re"
+#line 580 "ext/standard/var_unserializer.re"
 	{
 	*p = YYCURSOR;
 	INIT_PZVAL(*rval);
@@ -1117,7 +1123,7 @@ yy73:
 
 	return 1;
 }
-#line 1121 "ext/standard/var_unserializer.c"
+#line 1127 "ext/standard/var_unserializer.c"
 yy76:
 	yych = *++YYCURSOR;
 	if (yych == 'N') goto yy73;
@@ -1144,7 +1150,7 @@ yy79:
 	if (yych <= '9') goto yy79;
 	if (yych != ';') goto yy18;
 	++YYCURSOR;
-#line 550 "ext/standard/var_unserializer.re"
+#line 553 "ext/standard/var_unserializer.re"
 	{
 #if SIZEOF_LONG == 4
 	int digits = YYCURSOR - start - 3;
@@ -1171,7 +1177,7 @@ yy79:
 	ZVAL_LONG(*rval, parse_iv(start + 2));
 	return 1;
 }
-#line 1175 "ext/standard/var_unserializer.c"
+#line 1181 "ext/standard/var_unserializer.c"
 yy83:
 	yych = *++YYCURSOR;
 	if (yych <= '/') goto yy18;
@@ -1179,24 +1185,24 @@ yy83:
 	yych = *++YYCURSOR;
 	if (yych != ';') goto yy18;
 	++YYCURSOR;
-#line 543 "ext/standard/var_unserializer.re"
+#line 546 "ext/standard/var_unserializer.re"
 	{
 	*p = YYCURSOR;
 	INIT_PZVAL(*rval);
 	ZVAL_BOOL(*rval, parse_iv(start + 2));
 	return 1;
 }
-#line 1190 "ext/standard/var_unserializer.c"
+#line 1196 "ext/standard/var_unserializer.c"
 yy87:
 	++YYCURSOR;
-#line 536 "ext/standard/var_unserializer.re"
+#line 539 "ext/standard/var_unserializer.re"
 	{
 	*p = YYCURSOR;
 	INIT_PZVAL(*rval);
 	ZVAL_NULL(*rval);
 	return 1;
 }
-#line 1200 "ext/standard/var_unserializer.c"
+#line 1206 "ext/standard/var_unserializer.c"
 yy89:
 	yych = *++YYCURSOR;
 	if (yych <= ',') {
@@ -1219,7 +1225,7 @@ yy91:
 	if (yych <= '9') goto yy91;
 	if (yych != ';') goto yy18;
 	++YYCURSOR;
-#line 513 "ext/standard/var_unserializer.re"
+#line 516 "ext/standard/var_unserializer.re"
 	{
 	long id;
 
@@ -1242,7 +1248,7 @@ yy91:
 
 	return 1;
 }
-#line 1246 "ext/standard/var_unserializer.c"
+#line 1252 "ext/standard/var_unserializer.c"
 yy95:
 	yych = *++YYCURSOR;
 	if (yych <= ',') {
@@ -1265,7 +1271,7 @@ yy97:
 	if (yych <= '9') goto yy97;
 	if (yych != ';') goto yy18;
 	++YYCURSOR;
-#line 492 "ext/standard/var_unserializer.re"
+#line 495 "ext/standard/var_unserializer.re"
 	{
 	long id;
 
@@ -1278,7 +1284,7 @@ yy97:
 	}
 
 	if (*rval != NULL) {
-		zval_ptr_dtor(rval);
+		var_push_dtor_no_addref(var_hash, rval);
 	}
 	*rval = *rval_ref;
 	Z_ADDREF_PP(rval);
@@ -1286,9 +1292,9 @@ yy97:
 
 	return 1;
 }
-#line 1290 "ext/standard/var_unserializer.c"
+#line 1296 "ext/standard/var_unserializer.c"
 }
-#line 841 "ext/standard/var_unserializer.re"
+#line 847 "ext/standard/var_unserializer.re"
 
 
 	return 0;
diff --git a/ext/standard/var_unserializer.re b/ext/standard/var_unserializer.re
index f02602cd7e..ed821521e0 100644
--- a/ext/standard/var_unserializer.re
+++ b/ext/standard/var_unserializer.re
@@ -67,7 +67,7 @@ PHPAPI void var_push_dtor(php_unserialize_data_t *var_hashx, zval **rval)
 
 	var_hash = (*var_hashx)->last_dtor;
 #if VAR_ENTRIES_DBG
-	fprintf(stderr, "var_push_dtor(%ld): %d\n", var_hash?var_hash->used_slots:-1L, Z_TYPE_PP(rval));
+	fprintf(stderr, "var_push_dtor(%p, %ld): %d\n", *rval, var_hash?var_hash->used_slots:-1L, Z_TYPE_PP(rval));
 #endif
 
 	if (!var_hash || var_hash->used_slots == VAR_ENTRIES_MAX) {
@@ -98,7 +98,7 @@ PHPAPI void var_push_dtor_no_addref(php_unserialize_data_t *var_hashx, zval **rv
 
     var_hash = (*var_hashx)->last_dtor;
 #if VAR_ENTRIES_DBG
-	fprintf(stderr, "var_push_dtor_no_addref(%ld): %d (%d)\n", var_hash?var_hash->used_slots:-1L, Z_TYPE_PP(rval), Z_REFCOUNT_PP(rval));
+	fprintf(stderr, "var_push_dtor_no_addref(%p, %ld): %d (%d)\n", *rval, var_hash?var_hash->used_slots:-1L, Z_TYPE_PP(rval), Z_REFCOUNT_PP(rval));
 #endif
 
 	if (!var_hash || var_hash->used_slots == VAR_ENTRIES_MAX) {
@@ -177,6 +177,9 @@ PHPAPI void var_destroy(php_unserialize_data_t *var_hashx)
 
 	while (var_hash) {
 		for (i = 0; i < var_hash->used_slots; i++) {
+#if VAR_ENTRIES_DBG
+    fprintf(stderr, "var_destroy dtor(%p, %ld)\n", var_hash->data[i], Z_REFCOUNT_P(var_hash->data[i]));
+#endif
 			zval_ptr_dtor(&var_hash->data[i]);
 		}
 		next = var_hash->next;
@@ -501,7 +504,7 @@ PHPAPI int php_var_unserialize(UNSERIALIZE_PARAMETER)
 	}
 
 	if (*rval != NULL) {
-		zval_ptr_dtor(rval);
+		var_push_dtor_no_addref(var_hash, rval);
 	}
 	*rval = *rval_ref;
 	Z_ADDREF_PP(rval);
@@ -660,6 +663,7 @@ use_double:
 	long elements = parse_iv(start + 2);
 	/* use iv() not uiv() in order to check data range */
 	*p = YYCURSOR;
+    if (!var_hash) return 0;
 
 	if (elements < 0) {
 		return 0;
@@ -677,6 +681,7 @@ use_double:
 }
 
 "o:" iv ":" ["] {
+    if (!var_hash) return 0;
 
 	INIT_PZVAL(*rval);
 
@@ -699,6 +704,7 @@ object ":" uiv ":" ["]	{
 	zval **args[1];
 	zval *arg_func_name;
 
+    if (!var_hash) return 0;
 	if (*start == 'C') {
 		custom_object = 1;
 	}