[18/70] bridge: Fix possibly wrong MLD queries ethernet source address

[Greg KH]

2.6.38-stable review patch.  If anyone has any objections, please let us know.

------------------


From: Linus Lüssing <linus.luessing@xxxxxx>

[ Upstream commit a7bff75b087e7a355838a32efe61707cfa73c194 ]

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@xxxxxxxxxx>
Signed-off-by: Linus Lüssing <linus.luessing@xxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
 net/bridge/br_multicast.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -445,9 +445,9 @@ static struct sk_buff *br_ip6_multicast_
 	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);


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