net: Validate IFLA_BRIDGE_MODE attribute length

Payload is currently accessed blindly and may exceed valid message
boundaries.

Fixes: a77dcb8c8 ("be2net: set and query VEB/VEPA mode of the PF interface")
Fixes: 815cccbf1 ("ixgbe: add setlink, getlink support to ixgbe and ixgbevf")
Cc: Ajit Khaparde <ajit.khaparde@emulex.com>
Cc: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/emulex/benet/be_main.c b/drivers/net/ethernet/emulex/benet/be_main.c
index 3e8475c..337e4cd 100644
--- a/drivers/net/ethernet/emulex/benet/be_main.c
+++ b/drivers/net/ethernet/emulex/benet/be_main.c
@@ -4314,6 +4314,9 @@
 		if (nla_type(attr) != IFLA_BRIDGE_MODE)
 			continue;
 
+		if (nla_len(attr) < sizeof(mode))
+			return -EINVAL;
+
 		mode = nla_get_u16(attr);
 		if (mode != BRIDGE_MODE_VEPA && mode != BRIDGE_MODE_VEB)
 			return -EINVAL;