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Commit b7f8fe25 authored by Jiri Benc's avatar Jiri Benc Committed by David S. Miller
Browse files

gre: do not pull header in ICMP error processing 



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: bda7bb46 ("gre: Allow multiple protocol listener for gre protocol.")
Signed-off-by: default avatarJiri Benc <jbenc@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2c94b537

net/ipv4/ip_gre.c

+8 −3
Original line number Diff line number Diff line
@@ -179,6 +179,7 @@ static __be16 tnl_flags_to_gre_flags(__be16 tflags) 
	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_buff *skb, struct tnl_ptk_info *tpi, 
				return -EINVAL;

		}

	}

	return iptunnel_pull_header(skb, hdr_len, tpi->proto, false);

	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, u32 info) 
	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, false) < 0)

		goto drop;



	if (ipgre_rcv(skb, &tpi) == PACKET_RCVD)