ip6_gre: fix endianness errors in ip6gre_err

commit d1e158e2d7a0a91110b206653f0e02376e809150 upstream.

info is in network byte order, change it back to host byte order
before use. In particular, the current code sets the MTU of the tunnel
to a wrong (too big) value.

Fixes: c12b395a4664 ("gre: Support GRE over IPv6")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index ae88e17f5c721e7d8ae79b8c8f881382cc42fc29..529348e6a98be10576cff0835ab07db2a1fde703 100644 (file)
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -419,7 +419,7 @@ static void ip6gre_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
                if (code == ICMPV6_HDR_FIELD)
                        teli = ip6_tnl_parse_tlv_enc_lim(skb, skb->data);
 
-               if (teli && teli == info - 2) {
+               if (teli && teli == be32_to_cpu(info) - 2) {
                        tel = (struct ipv6_tlv_tnl_enc_lim *) &skb->data[teli];
                        if (tel->encap_limit == 0) {
                                net_warn_ratelimited("%s: Too small encapsulation limit or routing loop in tunnel!\n",
@@ -431,7 +431,7 @@ static void ip6gre_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
                }
                break;
        case ICMPV6_PKT_TOOBIG:
-               mtu = info - offset;
+               mtu = be32_to_cpu(info) - offset;
                if (mtu < IPV6_MIN_MTU)
                        mtu = IPV6_MIN_MTU;
                t->dev->mtu = mtu;