Commit message: Fix for bug #76582

The brigade seems to end up in a messed up state if something fails
in shutdown, so we clean it up.
CVE: CVE-2018-17082
CWE: CWE-79
Vulnerability description: The Apache2 component in PHP before 5.6.38, 7.0.x before 7.0.32, 7.1.x before 7.1.22, and 7.2.x before 7.2.10 allows XSS via the body of a "Transfer-Encoding: chunked" request, because the bucket brigade is mishandled in the php_handler function in sapi/apache2handler/sapi_apache2.c.

Project: php-src
File: sapi_apache2.c

static int php_handler(request_rec *r)
{
	php_struct * volatile ctx;
	void *conf;
	apr_bucket_brigade * volatile brigade;
	apr_bucket *bucket;
	apr_status_t rv;
	request_rec * volatile parent_req = NULL;
	TSRMLS_FETCH();

#define PHPAP_INI_OFF php_apache_ini_dtor(r, parent_req TSRMLS_CC);

	conf = ap_get_module_config(r->per_dir_config, &php5_module);

	/* apply_config() needs r in some cases, so allocate server_context early */
	ctx = SG(server_context);
	if (ctx == NULL || (ctx && ctx->request_processed && !strcmp(r->protocol, "INCLUDED"))) {
normal:
		ctx = SG(server_context) = apr_pcalloc(r->pool, sizeof(*ctx));
		/* register a cleanup so we clear out the SG(server_context)
		 * after each request. Note: We pass in the pointer to the
		 * server_context in case this is handled by a different thread.
		 */
		apr_pool_cleanup_register(r->pool, (void *)&SG(server_context), php_server_context_cleanup, apr_pool_cleanup_null);
		ctx->r = r;
		ctx = NULL; /* May look weird to null it here, but it is to catch the right case in the first_try later on */
	} else {
		parent_req = ctx->r;
		ctx->r = r;
	}
	apply_config(conf);

	if (strcmp(r->handler, PHP_MAGIC_TYPE) && strcmp(r->handler, PHP_SOURCE_MAGIC_TYPE) && strcmp(r->handler, PHP_SCRIPT)) {
		/* Check for xbithack in this case. */
		if (!AP2(xbithack) || strcmp(r->handler, "text/html") || !(r->finfo.protection & APR_UEXECUTE)) {
			PHPAP_INI_OFF;
			return DECLINED;
		}
	}

	/* Give a 404 if PATH_INFO is used but is explicitly disabled in
	 * the configuration; default behaviour is to accept. */
	if (r->used_path_info == AP_REQ_REJECT_PATH_INFO
		&& r->path_info && r->path_info[0]) {
		PHPAP_INI_OFF;
		return HTTP_NOT_FOUND;
	}

	/* handle situations where user turns the engine off */
	if (!AP2(engine)) {
		PHPAP_INI_OFF;
		return DECLINED;
	}

	if (r->finfo.filetype == 0) {
		php_apache_sapi_log_message_ex("script '%s' not found or unable to stat", r TSRMLS_CC);
		PHPAP_INI_OFF;
		return HTTP_NOT_FOUND;
	}
	if (r->finfo.filetype == APR_DIR) {
		php_apache_sapi_log_message_ex("attempt to invoke directory '%s' as script", r TSRMLS_CC);
		PHPAP_INI_OFF;
		return HTTP_FORBIDDEN;
	}

	/* Setup the CGI variables if this is the main request */
	if (r->main == NULL ||
		/* .. or if the sub-request environment differs from the main-request. */
		r->subprocess_env != r->main->subprocess_env
	) {
		/* setup standard CGI variables */
		ap_add_common_vars(r);
		ap_add_cgi_vars(r);
	}

zend_first_try {

	if (ctx == NULL) {
		brigade = apr_brigade_create(r->pool, r->connection->bucket_alloc);
		ctx = SG(server_context);
		ctx->brigade = brigade;

		if (php_apache_request_ctor(r, ctx TSRMLS_CC)!=SUCCESS) {
			zend_bailout();
		}
	} else {
		if (!parent_req) {
			parent_req = ctx->r;
		}
		if (parent_req && parent_req->handler &&
				strcmp(parent_req->handler, PHP_MAGIC_TYPE) &&
				strcmp(parent_req->handler, PHP_SOURCE_MAGIC_TYPE) &&
				strcmp(parent_req->handler, PHP_SCRIPT)) {
			if (php_apache_request_ctor(r, ctx TSRMLS_CC)!=SUCCESS) {
				zend_bailout();
			}
		}

		/*
		 * check if coming due to ErrorDocument
		 * We make a special exception of 413 (Invalid POST request) as the invalidity of the request occurs
		 * during processing of the request by PHP during POST processing. Therefor we need to re-use the exiting
		 * PHP instance to handle the request rather then creating a new one.
		*/
		if (parent_req && parent_req->status != HTTP_OK && parent_req->status != 413 && strcmp(r->protocol, "INCLUDED")) {
			parent_req = NULL;
			goto normal;
		}
		ctx->r = r;
		brigade = ctx->brigade;
	}

	if (AP2(last_modified)) {
		ap_update_mtime(r, r->finfo.mtime);
		ap_set_last_modified(r);
	}

	/* Determine if we need to parse the file or show the source */
	if (strncmp(r->handler, PHP_SOURCE_MAGIC_TYPE, sizeof(PHP_SOURCE_MAGIC_TYPE) - 1) == 0) {
		zend_syntax_highlighter_ini syntax_highlighter_ini;
		php_get_highlight_struct(&syntax_highlighter_ini);
		highlight_file((char *)r->filename, &syntax_highlighter_ini TSRMLS_CC);
	} else {
		zend_file_handle zfd;

		zfd.type = ZEND_HANDLE_FILENAME;
		zfd.filename = (char *) r->filename;
		zfd.free_filename = 0;
		zfd.opened_path = NULL;

		if (!parent_req) {
			php_execute_script(&zfd TSRMLS_CC);
		} else {
			zend_execute_scripts(ZEND_INCLUDE TSRMLS_CC, NULL, 1, &zfd);
		}

		apr_table_set(r->notes, "mod_php_memory_usage",
			apr_psprintf(ctx->r->pool, "%" APR_SIZE_T_FMT, zend_memory_peak_usage(1 TSRMLS_CC)));
	}

} zend_end_try();

 	if (!parent_req) {
 		php_apache_request_dtor(r TSRMLS_CC);
 		ctx->request_processed = 1;
 		bucket = apr_bucket_eos_create(r->connection->bucket_alloc);
 		APR_BRIGADE_INSERT_TAIL(brigade, bucket);
 
		rv = ap_pass_brigade(r->output_filters, brigade);
		if (rv != APR_SUCCESS || r->connection->aborted) {
zend_first_try {
			php_handle_aborted_connection();
} zend_end_try();
		}
		apr_brigade_cleanup(brigade);
		apr_pool_cleanup_run(r->pool, (void *)&SG(server_context), php_server_context_cleanup);
	} else {
		ctx->r = parent_req;
	}

	return OK;
}