From 6c03ee8bdaa10401f60dee25a719753d2fbbcc36 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Linus=20L=C3=BCssing?= Date: Thu, 12 Jun 2014 01:41:23 +0200 Subject: [PATCH] bridge: fix smatch warning / potential null pointer dereference MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit "New smatch warnings: net/bridge/br_multicast.c:1368 br_ip6_multicast_query() error: we previously assumed 'group' could be null (see line 1349)" In the rare (sort of broken) case of a query having a Maximum Response Delay of zero, we could create a potential null pointer dereference. Fixing this by skipping the multicast specific MLD Query parsing again if no multicast group address is available. Introduced by dc4eb53a996a78bfb8ea07b47423ff5a3aadc362 ("bridge: adhere to querier election mechanism specified by RFCs") Reported-by: Dan Carpenter Signed-off-by: Linus Lüssing Signed-off-by: David S. Miller --- net/bridge/br_multicast.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index cd3cf394c477..876e5fb2a786 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -1373,6 +1373,8 @@ static int br_ip6_multicast_query(struct net_bridge *br, br_multicast_query_received(br, port, &br->ip6_other_query, &saddr, max_delay); goto out; + } else if (!group) { + goto out; } mp = br_mdb_ip6_get(mlock_dereference(br->mdb, br), group, vid);