From 9cc906639d6cb4e2b4e4c6634fc56426f5894639 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 3.16: adjust context] Signed-off-by: Ben Hutchings --- include/net/ip6_tunnel.h | 1 + 1 file changed, 1 insertion(+) diff --git a/include/net/ip6_tunnel.h b/include/net/ip6_tunnel.h index ef9557683fec5..e2e680c02ff3d 100644 --- a/include/net/ip6_tunnel.h +++ b/include/net/ip6_tunnel.h @@ -75,6 +75,7 @@ static inline void ip6tunnel_xmit(struct sk_buff *skb, struct net_device *dev) struct net_device_stats *stats = &dev->stats; int pkt_len, err; + memset(skb->cb, 0, sizeof(struct inet6_skb_parm)); pkt_len = skb->len; err = ip6_local_out(skb); -- 2.47.3