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

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 <>
Signed-off-by: default avatarDavid S. Miller <>
parent 2c94b537
......@@ -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. */
......@@ -419,6 +420,7 @@ static int gre_rcv(struct sk_buff *skb)
struct tnl_ptk_info tpi;
bool csum_err = false;
int hdr_len;
if (ipv4_is_multicast(ip_hdr(skb)->daddr)) {
......@@ -428,7 +430,10 @@ static int gre_rcv(struct sk_buff *skb)
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)
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