bridge: fix mdb info leaks

The bridging code discloses heap and stack bytes via the RTM_GETMDB
netlink interface and via the notify messages send to group RTNLGRP_MDB
afer a successful add/del.

Fix both cases by initializing all unset members/padding bytes with
memset(0).

Cc: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 0 deletions

diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index 9f97b850fc65..ee79f3f20383 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -80,6 +80,7 @@ static int br_mdb_fill_info(struct sk_buff *skb, struct netlink_callback *cb,
                                 port = p->port;
                                 if (port) {
                                         struct br_mdb_entry e;
+                                        memset(&e, 0, sizeof(e));
                                         e.ifindex = port->dev->ifindex;
                                         e.state = p->state;
                                         if (p->addr.proto == htons(ETH_P_IP))
@@ -136,6 +137,7 @@ static int br_mdb_dump(struct sk_buff *skb, struct netlink_callback *cb)
                                 break;
 
                         bpm = nlmsg_data(nlh);
+                        memset(bpm, 0, sizeof(*bpm));
                         bpm->ifindex = dev->ifindex;
                         if (br_mdb_fill_info(skb, cb, dev) < 0)
                                 goto out;
@@ -171,6 +173,7 @@ static int nlmsg_populate_mdb_fill(struct sk_buff *skb,
                 return -EMSGSIZE;
 
         bpm = nlmsg_data(nlh);
+        memset(bpm, 0, sizeof(*bpm));
         bpm->family  = AF_BRIDGE;
         bpm->ifindex = dev->ifindex;
         nest = nla_nest_start(skb, MDBA_MDB);
@@ -228,6 +231,7 @@ void br_mdb_notify(struct net_device *dev, struct net_bridge_port *port,
 {
         struct br_mdb_entry entry;
 
+        memset(&entry, 0, sizeof(entry));
         entry.ifindex = port->dev->ifindex;
         entry.addr.proto = group->proto;
         entry.addr.u.ip4 = group->u.ip4;