Subject: [PATCH v2] ipv4: netfilter: always let NUL terminated string ended by '\0'

From: Chen Gang <[email-masked]>
Date: Thu, 23 May 2013 19:50:46 +0800

For NUL terminated string, need always be sure of ended by '\0'.

'prefix' max length is 128 (NF_LOG_PREFIXLEN), and 'pm->prefix' max
length is 32 (ULOG_PREFIX_LEN), so really need notice it.

'pm' is 'struct ulog_packet_msg_t' which may be copied to user mode
(defined in "include/uapi/..."), so can not use strlcpy() instead of.

Signed-off-by: Chen Gang <[email-masked]>
---
 net/ipv4/netfilter/ipt_ULOG.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/netfilter/ipt_ULOG.c b/net/ipv4/netfilter/ipt_ULOG.c
index cf08218..ff4b781 100644
--- a/net/ipv4/netfilter/ipt_ULOG.c
+++ b/net/ipv4/netfilter/ipt_ULOG.c
@@ -231,8 +231,10 @@ static void ipt_ulog_packet(struct net *net,
 	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
-- 
1.7.7.6