Commit 0e033e04 authored by Hannes Frederic Sowa's avatar Hannes Frederic Sowa Committed by David S. Miller

ipv6: fix headroom calculation in udp6_ufo_fragment

Commit 1e2bd517 ("udp6: Fix udp
fragmentation for tunnel traffic.") changed the calculation if
there is enough space to include a fragment header in the skb from a
skb->mac_header dervived one to skb_headroom. Because we already peeled
off the skb to transport_header this is wrong. Change this back to check
if we have enough room before the mac_header.

This fixes a panic Saran Neti reported. He used the tbf scheduler which
skb_gso_segments the skb. The offsets get negative and we panic in memcpy
because the skb was erroneously not expanded at the head.
Reported-by: default avatarSaran Neti <>
Cc: Pravin B Shelar <>
Signed-off-by: default avatarHannes Frederic Sowa <>
Signed-off-by: default avatarDavid S. Miller <>
parent 1cce16d3
......@@ -90,7 +90,7 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
/* Check if there is enough headroom to insert fragment header. */
tnl_hlen = skb_tnl_header_len(skb);
if (skb_headroom(skb) < (tnl_hlen + frag_hdr_sz)) {
if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
goto out;
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