netdev - [PATCH] bridge: Fix possibly wrong MLD queries' ethernet source address

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Message-Id: <1300830032-6727-2-git-send-email-linus.luessing@web.de>
Date:	Tue, 22 Mar 2011 22:40:32 +0100
From:	Linus Lüssing <linus.luessing@....de>
To:	Jan Beulich <JBeulich@...ell.com>
Cc:	<davem@...emloft.net>, <shemminger@...ux-foundation.org>,
	<bridge@...ts.linux-foundation.org>, <netdev@...r.kernel.org>,
	Linus Lüssing <linus.luessing@....de>
Subject: [PATCH] bridge: Fix possibly wrong MLD queries' ethernet source address

The ipv6_dev_get_saddr() is currently called with an uninitialized
destination address. Although in tests it usually seemed to nevertheless
always fetch the right source address, there seems to be a possible race
condition.

Therefore this commit changes this, first setting the destination
address and only after that fetching the source address.

Reported-by: Jan Beulich <JBeulich@...ell.com>
Signed-off-by: Linus Lüssing <linus.luessing@....de>
---
 net/bridge/br_multicast.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 030a002..f61eb2e 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -445,9 +445,9 @@ static struct sk_buff *br_ip6_multicast_alloc_query(struct net_bridge *br,
 	ip6h->payload_len = htons(8 + sizeof(*mldq));
 	ip6h->nexthdr = IPPROTO_HOPOPTS;
 	ip6h->hop_limit = 1;
+	ipv6_addr_set(&ip6h->daddr, htonl(0xff020000), 0, 0, htonl(1));
 	ipv6_dev_get_saddr(dev_net(br->dev), br->dev, &ip6h->daddr, 0,
 			   &ip6h->saddr);
-	ipv6_addr_set(&ip6h->daddr, htonl(0xff020000), 0, 0, htonl(1));
 	ipv6_eth_mc_map(&ip6h->daddr, eth->h_dest);
 
 	hopopt = (u8 *)(ip6h + 1);
-- 
1.5.6.5

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