Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758856AbaDVVd3 (ORCPT ); Tue, 22 Apr 2014 17:33:29 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:36171 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756762AbaDVUPM (ORCPT ); Tue, 22 Apr 2014 16:15:12 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Florian Westphal , Thomas Graf , Pablo Neira Ayuso , "David S. Miller" , Kamal Mostafa Subject: [PATCH 3.8 020/133] netlink: don't compare the nul-termination in nla_strcmp Date: Tue, 22 Apr 2014 13:12:38 -0700 Message-Id: <1398197671-12786-21-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1398197671-12786-1-git-send-email-kamal@canonical.com> References: <1398197671-12786-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.8.13.22 -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: Kamal Mostafa --- lib/nlattr.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/lib/nlattr.c b/lib/nlattr.c index 18eca78..fc67547 100644 --- a/lib/nlattr.c +++ b/lib/nlattr.c @@ -303,9 +303,15 @@ int nla_memcmp(const struct nlattr *nla, const void *data, */ 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); -- 1.9.1 -- 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/