ip_gre: fix parsing gre header in ipgre_err

gre_parse_header stops parsing when csum_err is encountered, which means
tpi->key is undefined and ip_tunnel_lookup will return NULL improperly.

This patch introduce a NULL pointer as csum_err parameter. Even when
csum_err is encountered, it won't return error and continue parsing gre
header as expected.

Fixes: 9f57c67c379d ("gre: Remove support for sharing GRE protocol hook.")
Reported-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c
index b798862..7efe740 100644 (file)
--- a/net/ipv4/gre_demux.c
+++ b/net/ipv4/gre_demux.c
@@ -86,13 +86,14 @@ int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
 
        options = (__be32 *)(greh + 1);
        if (greh->flags & GRE_CSUM) {
-               if (skb_checksum_simple_validate(skb)) {
+               if (!skb_checksum_simple_validate(skb)) {
+                       skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
+                                                null_compute_pseudo);
+               } else if (csum_err) {
                        *csum_err = true;
                        return -EINVAL;
                }
 
-               skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
-                                        null_compute_pseudo);
                options++;
        }
 

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 8cce0e9..c3385a8 100644 (file)
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -232,13 +232,10 @@ static void gre_err(struct sk_buff *skb, u32 info)
        const int type = icmp_hdr(skb)->type;
        const int code = icmp_hdr(skb)->code;
        struct tnl_ptk_info tpi;
-       bool csum_err = false;
 
-       if (gre_parse_header(skb, &tpi, &csum_err, htons(ETH_P_IP),
-                            iph->ihl * 4) < 0) {
-               if (!csum_err)          /* ignore csum errors. */
-                       return;
-       }
+       if (gre_parse_header(skb, &tpi, NULL, htons(ETH_P_IP),
+                            iph->ihl * 4) < 0)
+               return;
 
        if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
                ipv4_update_pmtu(skb, dev_net(skb->dev), info,