uri: Fix lexbor memory management in uri_parser_whatwg.c

Calling `lexbor_mraw_clean()` after a specific number of parses will destroy
the data for any live `Uri\WhatWg\Url` objects, effectively resulting in a
use-after-free.

Fix the issue by removing the periodic `lexbor_mraw_clean()` call.  Instead we
implement `php_uri_parser_whatwg_free()`. This also requires to move the
destruction of the lexbor structures from RSHUTDOWN to POST_ZEND_DEACTIVATE to
prevent a use-after-free in `php_uri_parser_whatwg_free()` since otherwise the
mraw would already have been destroyed.

Author: TimWolla

ext/uri/php_uri.c

@@ -1084,9 +1084,9 @@ PHP_RINIT_FUNCTION(uri)
 	return SUCCESS;
 }
 
-PHP_RSHUTDOWN_FUNCTION(uri)
+ZEND_MODULE_POST_ZEND_DEACTIVATE_D(uri)
 {
-	if (PHP_RSHUTDOWN(uri_parser_whatwg)(INIT_FUNC_ARGS_PASSTHRU) == FAILURE) {
+	if (ZEND_MODULE_POST_ZEND_DEACTIVATE_N(uri_parser_whatwg)() == FAILURE) {
 		return FAILURE;
 	}
 
@@ -1101,8 +1101,10 @@ zend_module_entry uri_module_entry = {
 	PHP_MINIT(uri),                 /* PHP_MINIT - Module initialization */
 	PHP_MSHUTDOWN(uri),             /* PHP_MSHUTDOWN - Module shutdown */
 	PHP_RINIT(uri),                 /* PHP_RINIT - Request initialization */
-	PHP_RSHUTDOWN(uri),             /* PHP_RSHUTDOWN - Request shutdown */
+	NULL,                           /* PHP_RSHUTDOWN - Request shutdown */
 	PHP_MINFO(uri),                 /* PHP_MINFO - Module info */
 	PHP_VERSION,                    /* Version */
-	STANDARD_MODULE_PROPERTIES
+	NO_MODULE_GLOBALS,
+	ZEND_MODULE_POST_ZEND_DEACTIVATE_N(uri),
+	STANDARD_MODULE_PROPERTIES_EX
 };

ext/uri/tests/056.phpt

@@ -0,0 +1,23 @@
+--TEST--
+Test Lexbor memory management
+--EXTENSIONS--
+uri
+--FILE--
+<?php
+
+$urls = [];
+
+for ($i = 0; $i < 1000; $i++) {
+    $urls[] = Uri\WhatWg\Url::parse("https://example.com/{$i}/");
+}
+
+for ($i = 0; $i < 1000; $i++) {
+    if ($urls[$i]->toAsciiString() !== "https://example.com/{$i}/") {
+        die("FAIL");
+    }
+}
+
+?>
+==DONE==
+--EXPECT--
+==DONE==

ext/uri/uri_parser_whatwg.c

@@ -24,10 +24,8 @@
 #include <arpa/inet.h>
 #endif
 
-ZEND_TLS lxb_url_parser_t lexbor_parser;
-ZEND_TLS unsigned short int parsed_urls;
+ZEND_TLS lxb_url_parser_t lexbor_parser = {0};
 
-static const unsigned short int maximum_parses_before_cleanup = 500;
 static const size_t lexbor_mraw_byte_size = 8192;
 
 static zend_always_inline void zval_string_or_null_to_lexbor_str(zval *value, lexbor_str_t *lexbor_str)
@@ -539,34 +537,20 @@ PHP_RINIT_FUNCTION(uri_parser_whatwg)
 		return FAILURE;
 	}
 
-	parsed_urls = 0;
-
 	return SUCCESS;
 }
 
-PHP_RSHUTDOWN_FUNCTION(uri_parser_whatwg)
+ZEND_MODULE_POST_ZEND_DEACTIVATE_D(uri_parser_whatwg)
 {
 	lxb_url_parser_memory_destroy(&lexbor_parser);
 	lxb_url_parser_destroy(&lexbor_parser, false);
 
-	parsed_urls = 0;
-
 	return SUCCESS;
 }
 
-static void reset_parser_state(void)
-{
-	if (++parsed_urls % maximum_parses_before_cleanup == 0) {
-		lexbor_mraw_clean(lexbor_parser.mraw);
-		parsed_urls = 0;
-	}
-
-	lxb_url_parser_clean(&lexbor_parser);
-}
-
 lxb_url_t *php_uri_parser_whatwg_parse_ex(const char *uri_str, size_t uri_str_len, const lxb_url_t *lexbor_base_url, zval *errors, bool silent)
 {
-	reset_parser_state();
+	lxb_url_parser_clean(&lexbor_parser);
 
 	lxb_url_t *url = lxb_url_parse(&lexbor_parser, lexbor_base_url, (unsigned char *) uri_str, uri_str_len);
 	const char *reason = fill_errors(errors);
@@ -619,6 +603,9 @@ static zend_string *php_uri_parser_whatwg_to_string(void *uri, uri_recomposition
 
 static void php_uri_parser_whatwg_free(void *uri)
 {
+	lxb_url_t *lexbor_uri = uri;
+
+	lxb_url_destroy(lexbor_uri);
 }
 
 const uri_parser_t php_uri_parser_whatwg = {

ext/uri/uri_parser_whatwg.h

@@ -25,6 +25,6 @@ extern const uri_parser_t php_uri_parser_whatwg;
 lxb_url_t *php_uri_parser_whatwg_parse_ex(const char *uri_str, size_t uri_str_len, const lxb_url_t *lexbor_base_url, zval *errors, bool silent);
 
 PHP_RINIT_FUNCTION(uri_parser_whatwg);
-PHP_RSHUTDOWN_FUNCTION(uri_parser_whatwg);
+ZEND_MODULE_POST_ZEND_DEACTIVATE_D(uri_parser_whatwg);
 
 #endif