linux-kernel - [PATCH 140/173] netfilter: ipt_CLUSTERIP: fix buffer overflow

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Date:	Mon, 25 Apr 2011 22:04:52 +0200
From:	Willy Tarreau <w@....eu>
To:	linux-kernel@...r.kernel.org, stable@...nel.org,
	stable-review@...nel.org
Cc:	Vasiliy Kulikov <segoon@...nwall.com>,
	Changli Gao <xiaosuo@...il.com>,
	Patrick McHardy <kaber@...sh.net>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: [PATCH 140/173] netfilter: ipt_CLUSTERIP: fix buffer overflow

2.6.27.59-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Vasiliy Kulikov <segoon@...nwall.com>

commit 961ed183a9fd080cf306c659b8736007e44065a5 upstream.

'buffer' string is copied from userspace.  It is not checked whether it is
zero terminated.  This may lead to overflow inside of simple_strtoul().
Changli Gao suggested to copy not more than user supplied 'size' bytes.

It was introduced before the git epoch.  Files "ipt_CLUSTERIP/*" are
root writable only by default, however, on some setups permissions might be
relaxed to e.g. network admin user.

Signed-off-by: Vasiliy Kulikov <segoon@...nwall.com>
Acked-by: Changli Gao <xiaosuo@...il.com>
Signed-off-by: Patrick McHardy <kaber@...sh.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 net/ipv4/netfilter/ipt_CLUSTERIP.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
+++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
@@ -666,8 +666,11 @@ static ssize_t clusterip_proc_write(stru
 	struct clusterip_config *c = pde->data;
 	unsigned long nodenum;
 
-	if (copy_from_user(buffer, input, PROC_WRITELEN))
+	if (size > PROC_WRITELEN)
+		return -EIO;
+	if (copy_from_user(buffer, input, size))
 		return -EFAULT;
+	buffer[size] = 0;
 
 	if (*buffer == '+') {
 		nodenum = simple_strtoul(buffer+1, NULL, 10);


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