4.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Eric Dumazet <[email protected]> [ Upstream commit 21b995a9cb093fff33ec91d7cb3822b882a90a1e ] Since ip6_tnl_parse_tlv_enc_lim() can call pskb_may_pull(), we must reload any pointer that was related to skb->head (or skb->data), or risk use after free. Fixes: c12b395a4664 ("gre: Support GRE over IPv6") Signed-off-by: Eric Dumazet <[email protected]> Cc: Dmitry Kozlov <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Sasha Levin <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- net/ipv6/ip6_gre.c | 3 +++ net/ipv6/ip6_tunnel.c | 2 ++ 2 files changed, 5 insertions(+) --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -582,6 +582,9 @@ static inline int ip6gre_xmit_ipv6(struc return -1; offset = ip6_tnl_parse_tlv_enc_lim(skb, skb_network_header(skb)); + /* ip6_tnl_parse_tlv_enc_lim() might have reallocated skb->head */ + ipv6h = ipv6_hdr(skb); + if (offset > 0) { struct ipv6_tlv_tnl_enc_lim *tel; tel = (struct ipv6_tlv_tnl_enc_lim *)&skb_network_header(skb)[offset]; --- a/net/ipv6/ip6_tunnel.c +++ b/net/ipv6/ip6_tunnel.c @@ -1313,6 +1313,8 @@ ip6ip6_tnl_xmit(struct sk_buff *skb, str fl6.flowlabel = key->label; } else { offset = ip6_tnl_parse_tlv_enc_lim(skb, skb_network_header(skb)); + /* ip6_tnl_parse_tlv_enc_lim() might have reallocated skb->head */ + ipv6h = ipv6_hdr(skb); if (offset > 0) { struct ipv6_tlv_tnl_enc_lim *tel;
