From: Cong Wang <[email protected]>

[ Upstream commit 085c7c4e1c0e50d90b7d90f61a12e12b317a91e2 ]

Both version 0 and version 1 use ETH_P_ERSPAN, but version 0 does not
have an erspan header. So the check in gre_parse_header() is wrong,
we have to distinguish version 1 from version 0.

We can just check the gre header length like is_erspan_type1().

Fixes: cb73ee40b1b3 ("net: ip_gre: use erspan key field for tunnel lookup")
Reported-by: [email protected]
Cc: William Tu <[email protected]>
Cc: Lorenzo Bianconi <[email protected]>
Signed-off-by: Cong Wang <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 net/ipv4/gre_demux.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ipv4/gre_demux.c
+++ b/net/ipv4/gre_demux.c
@@ -128,7 +128,7 @@ int gre_parse_header(struct sk_buff *skb
         * to 0 and sets the configured key in the
         * inner erspan header field
         */
-       if (greh->protocol == htons(ETH_P_ERSPAN) ||
+       if ((greh->protocol == htons(ETH_P_ERSPAN) && hdr_len != 4) ||
            greh->protocol == htons(ETH_P_ERSPAN2)) {
                struct erspan_base_hdr *ershdr;
 


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