Add mitigation for CVE-2015-0235 (bug #68925)

Author: smalyshev

NEWS

@@ -2,6 +2,10 @@ PHP                                                                        NEWS
 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 ?? ??? 20?? PHP 5.4.38
 
+- Core:
+  . Fixed bug #68925 (Mitigation for CVE-2015-0235 – GHOST: glibc gethostbyname
+    buffer overflow). (Stas)
+
 22 Jan 2015 PHP 5.4.37
 - Core:
   . Fixed bug #68710 (Use After Free Vulnerability in PHP's unserialize()).

ext/standard/dns.c

@@ -222,6 +222,11 @@ PHP_FUNCTION(gethostbyname)
 		return;
 	}
 
+	if(hostname_len > MAXHOSTNAMELEN) {
+		/* name too long, protect from CVE-2015-0235 */
+		php_error_docref(NULL, E_WARNING, "Host name is too long, the limit is %d characters", MAXHOSTNAMELEN);
+		RETURN_STRINGL(hostname, hostname_len, 1);
+	}
 	addr = php_gethostbyname(hostname);
 
 	RETVAL_STRING(addr, 0);
@@ -242,6 +247,12 @@ PHP_FUNCTION(gethostbynamel)
 		return;
 	}
 
+	if(hostname_len > MAXHOSTNAMELEN) {
+		/* name too long, protect from CVE-2015-0235 */
+		php_error_docref(NULL, E_WARNING, "Host name is too long, the limit is %d characters", MAXHOSTNAMELEN);
+		RETURN_FALSE;
+	}
+
 	hp = gethostbyname(hostname);
 	if (hp == NULL || hp->h_addr_list == NULL) {
 		RETURN_FALSE;

ext/standard/tests/network/bug68925.phpt

@@ -0,0 +1,13 @@
+--TEST--
+Bug #68925 (CVE-2015-0235 – GHOST: glibc gethostbyname buffer overflow)
+--FILE--
+<?php
+var_dump(gethostbyname(str_repeat("0", 2501)));
+var_dump(gethostbynamel(str_repeat("0", 2501)));
+?>
+--EXPECTF--
+Warning: gethostbyname(): Host name is too long, the limit is 256 characters in %s/bug68925.php on line %d
+string(2501) "00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
+
+Warning: gethostbynamel(): Host name is too long, the limit is 256 characters in %s/bug68925.php on line %d
+bool(false)

main/network.c

@@ -24,6 +24,7 @@
 #include "php.h"
 
 #include <stddef.h>
+#include <errno.h>
 
 #ifdef PHP_WIN32
 # include "win32/inet.h"
@@ -102,6 +103,10 @@ const struct in6_addr in6addr_any = {0}; /* IN6ADDR_ANY_INIT; */
 # define PHP_TIMEOUT_ERROR_VALUE		ETIMEDOUT
 #endif
 
+#ifndef MAXHOSTNAMELEN
+#define MAXHOSTNAMELEN 255
+#endif
+
 #if HAVE_GETADDRINFO
 #ifdef HAVE_GAI_STRERROR
 #  define PHP_GAI_STRERROR(x) (gai_strerror(x))
@@ -243,7 +248,12 @@ PHPAPI int php_network_getaddresses(const char *host, int socktype, struct socka
 #else
 	if (!inet_aton(host, &in)) {
 		/* XXX NOT THREAD SAFE (is safe under win32) */
-		host_info = gethostbyname(host);
+		if(strlen(host) > MAXHOSTNAMELEN) {
+			host_info = NULL;
+			errno = E2BIG;
+		} else {
+			host_info = gethostbyname(host);
+		}
 		if (host_info == NULL) {
 			if (error_string) {
 				spprintf(error_string, 0, "php_network_getaddresses: gethostbyname failed. errno=%d", errno);

sapi/cgi/fastcgi.c

@@ -611,7 +611,11 @@ int fcgi_listen(const char *path, int backlog)
 			if (sa.sa_inet.sin_addr.s_addr == INADDR_NONE) {
 				struct hostent *hep;
 
-				hep = gethostbyname(host);
+				if(strlen(host) > MAXHOSTNAMELEN) {
+					hep = NULL;
+				} else {
+					hep = gethostbyname(host);
+				}
 				if (!hep || hep->h_addrtype != AF_INET || !hep->h_addr_list[0]) {
 					fprintf(stderr, "Cannot resolve host name '%s'!\n", host);
 					return -1;