From d8cf27287ac7fb5cbfcc4139917a997c39d841ca Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Sat, 19 May 2007 14:44:15 -0700 Subject: [PATCH] [IPV4]: icmp: fix crash with sysctl_icmp_errors_use_inbound_ifaddr When icmp_send is called on the local output path before the packet hits ip_output, skb->dev is not set, causing a crash when sysctl_icmp_errors_use_inbound_ifaddr is set. This can happen with the netfilter REJECT target or IPsec tunnels. Let routing decide the ICMP source address in that case, since the packet is locally generated there is no inbound interface and the sysctl should not apply. The option actually seems to be unfixable broken, on the path after ip_output() skb->dev points to the outgoing device and we don't know the incoming device anymore, so its going to do the absolute wrong thing and pick the address of the outgoing interface. Add a comment about this. Reported by Curtis Doty . Signed-off-by: Patrick McHardy Signed-off-by: David S. Miller --- net/ipv4/icmp.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c index d38cbba92a4d..e238b17f554c 100644 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@ -514,7 +514,10 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info) saddr = iph->daddr; if (!(rt->rt_flags & RTCF_LOCAL)) { - if (sysctl_icmp_errors_use_inbound_ifaddr) + /* This is broken, skb_in->dev points to the outgoing device + * after the packet passes through ip_output(). + */ + if (skb_in->dev && sysctl_icmp_errors_use_inbound_ifaddr) saddr = inet_select_addr(skb_in->dev, 0, RT_SCOPE_LINK); else saddr = 0; -- 2.20.1