vxlan: use the correct nlattr array in NL_SET_ERR_MSG_ATTR

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

Fixes: 653ef6a3 ("vxlan: change vxlan_[config_]validate() to use netlink_ext_ack for error reporting")
Fixes: b4d30697 ("vxlan: Allow configuration of DF behaviour")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vxlan.c

@@ -3144,7 +3144,7 @@ static int vxlan_validate(struct nlattr *tb[], struct nlattr *data[],
 		u32 id = nla_get_u32(data[IFLA_VXLAN_ID]);
 
 		if (id >= VXLAN_N_VID) {
-			NL_SET_ERR_MSG_ATTR(extack, tb[IFLA_VXLAN_ID],
+			NL_SET_ERR_MSG_ATTR(extack, data[IFLA_VXLAN_ID],
 					    "VXLAN ID must be lower than 16777216");
 			return -ERANGE;
 		}
@@ -3155,7 +3155,7 @@ static int vxlan_validate(struct nlattr *tb[], struct nlattr *data[],
 			= nla_data(data[IFLA_VXLAN_PORT_RANGE]);
 
 		if (ntohs(p->high) < ntohs(p->low)) {
-			NL_SET_ERR_MSG_ATTR(extack, tb[IFLA_VXLAN_PORT_RANGE],
+			NL_SET_ERR_MSG_ATTR(extack, data[IFLA_VXLAN_PORT_RANGE],
 					    "Invalid source port range");
 			return -EINVAL;
 		}
@@ -3165,7 +3165,7 @@ static int vxlan_validate(struct nlattr *tb[], struct nlattr *data[],
 		enum ifla_vxlan_df df = nla_get_u8(data[IFLA_VXLAN_DF]);
 
 		if (df < 0 || df > VXLAN_DF_MAX) {
-			NL_SET_ERR_MSG_ATTR(extack, tb[IFLA_VXLAN_DF],
+			NL_SET_ERR_MSG_ATTR(extack, data[IFLA_VXLAN_DF],
 					    "Invalid DF attribute");
 			return -EINVAL;
 		}