Patchwork [41/98] netfilter: ipt_ULOG: fix non-null terminated string in the nf_log path

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Submitter Luis Henriques
Date July 11, 2013, 2:24 p.m.
Message ID <1373552708-15235-42-git-send-email-luis.henriques@canonical.com>
Download mbox | patch
Permalink /patch/258503/
State New
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Luis Henriques - July 11, 2013, 2:24 p.m.
3.5.7.17 -stable review patch.  If anyone has any objections, please let me know.

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

From: Chen Gang <gang.chen@asianux.com>

commit 4f36ea6eed2081340c7a7aa98c73187ecfccebff upstream.

If nf_log uses ipt_ULOG as logging output, we can deliver non-null
terminated strings to user-space since the maximum length of the
prefix that is passed by nf_log is NF_LOG_PREFIXLEN but pm->prefix
is 32 bytes long (ULOG_PREFIX_LEN).

This is actually happening already from nf_conntrack_tcp if ipt_ULOG
is used, since it is passing strings longer than 32 bytes.

Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 net/ipv4/netfilter/ipt_ULOG.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Patch

diff --git a/net/ipv4/netfilter/ipt_ULOG.c b/net/ipv4/netfilter/ipt_ULOG.c
index ba5756d..60d2bba 100644
--- a/net/ipv4/netfilter/ipt_ULOG.c
+++ b/net/ipv4/netfilter/ipt_ULOG.c
@@ -214,8 +214,10 @@  static void ipt_ulog_packet(unsigned int hooknum,
 	put_unaligned(tv.tv_usec, &pm->timestamp_usec);
 	put_unaligned(skb->mark, &pm->mark);
 	pm->hook = hooknum;
-	if (prefix != NULL)
-		strncpy(pm->prefix, prefix, sizeof(pm->prefix));
+	if (prefix != NULL) {
+		strncpy(pm->prefix, prefix, sizeof(pm->prefix) - 1);
+		pm->prefix[sizeof(pm->prefix) - 1] = '\0';
+	}
 	else if (loginfo->prefix[0] != '\0')
 		strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix));
 	else