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>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/ipv4/netfilter/ipt_ULOG.c b/net/ipv4/netfilter/ipt_ULOG.c
index b550815..c3b44d5 100644 (file)
--- a/net/ipv4/netfilter/ipt_ULOG.c
+++ b/net/ipv4/netfilter/ipt_ULOG.c
@@ -202,6 +202,7 @@ static void ipt_ulog_packet(unsigned int hooknum,
        ub->qlen++;
 
        pm = NLMSG_DATA(nlh);
+       memset(pm, 0, sizeof(*pm));
 
        /* We might not have a timestamp, get one */
        if (skb->tstamp.tv64 == 0)
@@ -218,8 +219,6 @@ static void ipt_ulog_packet(unsigned int hooknum,
                strncpy(pm->prefix, prefix, sizeof(pm->prefix));
        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 &&
@@ -231,13 +230,9 @@ static void ipt_ulog_packet(unsigned int hooknum,
 
        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)