geneve: use the correct nlattr array in NL_SET_ERR_MSG_ATTR

IFLA_GENEVE_* attributes are in the data array, which is correctly
used when fetching the value, but not when setting the extended
ack. Because IFLA_GENEVE_MAX < IFLA_MAX, we avoid out of bounds
array accesses, but we don't provide a pointer to the invalid
attribute to userspace.

Fixes: a025fb5f49 ("geneve: Allow configuration of DF behaviour")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/geneve.c

@@ -1207,7 +1207,7 @@ static int geneve_validate(struct nlattr *tb[], struct nlattr *data[],
 		enum ifla_geneve_df df = nla_get_u8(data[IFLA_GENEVE_DF]);
 
 		if (df < 0 || df > GENEVE_DF_MAX) {
-			NL_SET_ERR_MSG_ATTR(extack, tb[IFLA_GENEVE_DF],
+			NL_SET_ERR_MSG_ATTR(extack, data[IFLA_GENEVE_DF],
 					    "Invalid DF attribute");
 			return -EINVAL;
 		}