netfilter: ipt_ULOG: fix info leaks

commit 278f2b3e2af5f32ea1afe34fa12a2518153e6e49 upstream.

The ulog messages leak heap bytes by the means of padding bytes and
incompletely filled string arrays. Fix those by memset(0)'ing the
whole struct before filling it.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

diff --git a/net/ipv4/netfilter/ipt_ULOG.c b/net/ipv4/netfilter/ipt_ULOG.c
index cbc22158af490589833a4918f3610050a60d5be4..9cb993cd224bf702ca48382a0656163837433c54 100644 (file)
--- a/net/ipv4/netfilter/ipt_ULOG.c
+++ b/net/ipv4/netfilter/ipt_ULOG.c
@@ -220,6 +220,7 @@ static void ipt_ulog_packet(struct net *net,
        ub->qlen++;
 
        pm = nlmsg_data(nlh);
+       memset(pm, 0, sizeof(*pm));
 
        /* We might not have a timestamp, get one */
        if (skb->tstamp.tv64 == 0)
@@ -238,8 +239,6 @@ static void ipt_ulog_packet(struct net *net,
        }
        else if (loginfo->prefix[0] != '\0')
                strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix));
-       else
-               *(pm->prefix) = '\0';
 
        if (in && in->hard_header_len > 0 &&
            skb->mac_header != skb->network_header &&
@@ -251,13 +250,9 @@ static void ipt_ulog_packet(struct net *net,
 
        if (in)
                strncpy(pm->indev_name, in->name, sizeof(pm->indev_name));
-       else
-               pm->indev_name[0] = '\0';
 
        if (out)
                strncpy(pm->outdev_name, out->name, sizeof(pm->outdev_name));
-       else
-               pm->outdev_name[0] = '\0';
 
        /* copy_len <= skb->len, so can't fail. */
        if (skb_copy_bits(skb, 0, pm->payload, copy_len) < 0)