From 192db9b925b664c39a04baa9f865f8ca64743f86 Mon Sep 17 00:00:00 2001 From: Eli Cooper Date: Tue, 1 Nov 2016 23:45:12 +0800 Subject: [PATCH] ip6_tunnel: Clear IP6CB in ip6tunnel_xmit() commit 23f4ffedb7d751c7e298732ba91ca75d224bc1a6 upstream. skb->cb may contain data from previous layers. In the observed scenario, the garbage data were misinterpreted as IP6CB(skb)->frag_max_size, so that small packets sent through the tunnel are mistakenly fragmented. This patch unconditionally clears the control buffer in ip6tunnel_xmit(), which affects ip6_tunnel, ip6_udp_tunnel and ip6_gre. Currently none of these tunnels set IP6CB(skb)->flags, otherwise it needs to be done earlier. Signed-off-by: Eli Cooper Signed-off-by: David S. Miller [bwh: Backported to 3.2: apply to ip6_tnl_xmit2()] Signed-off-by: Ben Hutchings --- net/ipv6/ip6_tunnel.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c index 1828c27ba7aa..741917c3aa5d 100644 --- a/net/ipv6/ip6_tunnel.c +++ b/net/ipv6/ip6_tunnel.c @@ -983,6 +983,7 @@ static int ip6_tnl_xmit2(struct sk_buff *skb, ipv6_addr_copy(&ipv6h->saddr, &fl6->saddr); ipv6_addr_copy(&ipv6h->daddr, &fl6->daddr); nf_reset(skb); + memset(skb->cb, 0, sizeof(struct inet6_skb_parm)); pkt_len = skb->len; err = ip6_local_out(skb); -- 2.39.2