[PATCH net-next] erspan: Check IFLA_GRE_ERSPAN_VER is set.

[William Tu]

Add a check to make sure the IFLA_GRE_ERSPAN_VER is provided by users.

Fixes: f989d546a2d5 ("erspan: Add type I version 0 support.")
Cc: Eric Dumazet <eric.duma...@gmail.com>
Signed-off-by: William Tu <u9012...@gmail.com>
---
 net/ipv4/ip_gre.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index e29cd48674d7..0ce9b91ff55c 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -1087,7 +1087,8 @@ static int erspan_validate(struct nlattr *tb[], struct 
nlattr *data[],
        if (ret)
                return ret;
 
-       if (nla_get_u8(data[IFLA_GRE_ERSPAN_VER]) == 0)
+       if (data[IFLA_GRE_ERSPAN_VER] &&
+           nla_get_u8(data[IFLA_GRE_ERSPAN_VER]) == 0)
                return 0;
 
        /* ERSPAN type II/III should only have GRE sequence and key flag */
-- 
2.7.4