path: root/net
diff options
authorHerbert Xu <herbert@gondor.apana.org.au>2011-02-11 12:36:55 +0000
committerDavid S. Miller <davem@davemloft.net>2011-02-11 21:59:37 -0800
commit6b0d6a9b4296fa16a28d10d416db7a770fc03287 (patch)
tree27f21e7dbcd447e7fd0f2d0b75e2c9cd9e7deddf /net
parentip_gre: Add IPPROTO_GRE to flowi in ipgre_tunnel_xmit (diff)
bridge: Fix mglist corruption that leads to memory corruption
The list mp->mglist is used to indicate whether a multicast group is active on the bridge interface itself as opposed to one of the constituent interfaces in the bridge. Unfortunately the operation that adds the mp->mglist node to the list neglected to check whether it has already been added. This leads to list corruption in the form of nodes pointing to itself. Normally this would be quite obvious as it would cause an infinite loop when walking the list. However, as this list is never actually walked (which means that we don't really need it, I'll get rid of it in a subsequent patch), this instead is hidden until we perform a delete operation on the affected nodes. As the same node may now be pointed to by more than one node, the delete operations can then cause modification of freed memory. This was observed in practice to cause corruption in 512-byte slabs, most commonly leading to crashes in jbd2. Thanks to Josef Bacik for pointing me in the right direction. Reported-by: Ian Page Hands <ihands@redhat.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
1 files changed, 2 insertions, 1 deletions
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index f701a21acb34..fdbd41c76ec4 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -719,7 +719,8 @@ static int br_multicast_add_group(struct net_bridge *br,
goto err;
if (!port) {
- hlist_add_head(&mp->mglist, &br->mglist);
+ if (hlist_unhashed(&mp->mglist))
+ hlist_add_head(&mp->mglist, &br->mglist);
mod_timer(&mp->timer, now + br->multicast_membership_interval);
goto out;