bridge: reset IPCB in br_parse_ip_options

Commit 462fb2af9788a82 (bridge : Sanitize skb before it enters the IP
stack), missed one IPCB init before calling ip_options_compile()

Thanks to Scot Doyle for his tests and bug reports.

Reported-by: Scot Doyle <lkml@scotdoyle.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Hiroaki SHIMODA <shimoda.hiroaki@gmail.com>
Acked-by: Bandan Das <bandan.das@stratus.com>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Cc: Jan Lübbe <jluebbe@debian.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_netfilter.c

@@ -249,11 +249,9 @@ static int br_parse_ip_options(struct sk_buff *skb)
 		goto drop;
 	}
 
-	/* Zero out the CB buffer if no options present */
-	if (iph->ihl == 5) {
-		memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
+	memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
+	if (iph->ihl == 5)
 		return 0;
-	}
 
 	opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
 	if (ip_options_compile(dev_net(dev), opt, skb))