Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932174AbaDXV6e (ORCPT ); Thu, 24 Apr 2014 17:58:34 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:39862 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757031AbaDXVxU (ORCPT ); Thu, 24 Apr 2014 17:53:20 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Florian Westphal , Thomas Graf , Pablo Neira Ayuso , "David S. Miller" Subject: [PATCH 3.4 13/27] netlink: dont compare the nul-termination in nla_strcmp Date: Thu, 24 Apr 2014 14:55:47 -0700 Message-Id: <20140424215552.353046321@linuxfoundation.org> X-Mailer: git-send-email 1.9.0 In-Reply-To: <20140424215551.942390050@linuxfoundation.org> References: <20140424215551.942390050@linuxfoundation.org> User-Agent: quilt/0.61-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pablo Neira [ Upstream commit 8b7b932434f5eee495b91a2804f5b64ebb2bc835 ] nla_strcmp compares the string length plus one, so it's implicitly including the nul-termination in the comparison. int nla_strcmp(const struct nlattr *nla, const char *str) { int len = strlen(str) + 1; ... d = memcmp(nla_data(nla), str, len); However, if NLA_STRING is used, userspace can send us a string without the nul-termination. This is a problem since the string comparison will not match as the last byte may be not the nul-termination. Fix this by skipping the comparison of the nul-termination if the attribute data is nul-terminated. Suggested by Thomas Graf. Cc: Florian Westphal Cc: Thomas Graf Signed-off-by: Pablo Neira Ayuso Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- lib/nlattr.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/lib/nlattr.c +++ b/lib/nlattr.c @@ -299,9 +299,15 @@ int nla_memcmp(const struct nlattr *nla, */ int nla_strcmp(const struct nlattr *nla, const char *str) { - int len = strlen(str) + 1; - int d = nla_len(nla) - len; + int len = strlen(str); + char *buf = nla_data(nla); + int attrlen = nla_len(nla); + int d; + if (attrlen > 0 && buf[attrlen - 1] == '\0') + attrlen--; + + d = attrlen - len; if (d == 0) d = memcmp(nla_data(nla), str, len); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/