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Message-Id: <1398197671-12786-21-git-send-email-kamal@canonical.com>
Date: Tue, 22 Apr 2014 13:12:38 -0700
From: Kamal Mostafa <kamal@...onical.com>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
kernel-team@...ts.ubuntu.com
Cc: Florian Westphal <fw@...len.de>, Thomas Graf <tgraf@...g.ch>,
Pablo Neira Ayuso <pablo@...filter.org>,
"David S. Miller" <davem@...emloft.net>,
Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.8 020/133] netlink: don't compare the nul-termination in nla_strcmp
3.8.13.22 -stable review patch. If anyone has any objections, please let me know.
------------------
From: Pablo Neira <pablo@...filter.org>
[ 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 <fw@...len.de>
Cc: Thomas Graf <tgraf@...g.ch>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
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
--
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