4.5-stable review patch. If anyone has any objections, please let me know.
------------------ From: Jiri Benc <[email protected]> [ Upstream commit b7f8fe251e4609e2a437bd2c2dea01e61db6849c ] iptunnel_pull_header expects that IP header was already pulled; with this expectation, it pulls the tunnel header. This is not true in gre_err. Furthermore, ipv4_update_pmtu and ipv4_redirect expect that skb->data points to the IP header. We cannot pull the tunnel header in this path. It's just a matter of not calling iptunnel_pull_header - we don't need any of its effects. Fixes: bda7bb463436 ("gre: Allow multiple protocol listener for gre protocol.") Signed-off-by: Jiri Benc <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- net/ipv4/ip_gre.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -179,6 +179,7 @@ static __be16 tnl_flags_to_gre_flags(__b return flags; } +/* Fills in tpi and returns header length to be pulled. */ static int parse_gre_header(struct sk_buff *skb, struct tnl_ptk_info *tpi, bool *csum_err) { @@ -238,7 +239,7 @@ static int parse_gre_header(struct sk_bu return -EINVAL; } } - return iptunnel_pull_header(skb, hdr_len, tpi->proto); + return hdr_len; } static void ipgre_err(struct sk_buff *skb, u32 info, @@ -341,7 +342,7 @@ static void gre_err(struct sk_buff *skb, struct tnl_ptk_info tpi; bool csum_err = false; - if (parse_gre_header(skb, &tpi, &csum_err)) { + if (parse_gre_header(skb, &tpi, &csum_err) < 0) { if (!csum_err) /* ignore csum errors. */ return; } @@ -419,6 +420,7 @@ static int gre_rcv(struct sk_buff *skb) { struct tnl_ptk_info tpi; bool csum_err = false; + int hdr_len; #ifdef CONFIG_NET_IPGRE_BROADCAST if (ipv4_is_multicast(ip_hdr(skb)->daddr)) { @@ -428,7 +430,10 @@ static int gre_rcv(struct sk_buff *skb) } #endif - if (parse_gre_header(skb, &tpi, &csum_err) < 0) + hdr_len = parse_gre_header(skb, &tpi, &csum_err); + if (hdr_len < 0) + goto drop; + if (iptunnel_pull_header(skb, hdr_len, tpi.proto) < 0) goto drop; if (ipgre_rcv(skb, &tpi) == PACKET_RCVD)
