tipc: don't sanity check non-existing TLV (NL compat)

A zero length payload means that no TLV (Type Length Value) data has
been passed. Prior to this patch a non-existing TLV could be sanity
checked with TLV_OK() resulting in random behavior where a user
sending an empty message occasionally got a incorrect "operation not
supported" message back.

Signed-off-by: Richard Alpe <richard.alpe@ericsson.com>
Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/tipc/netlink_compat.c b/net/tipc/netlink_compat.c
index 53e0fee80086..1eadc95e1132 100644
--- a/net/tipc/netlink_compat.c
+++ b/net/tipc/netlink_compat.c
@@ -1114,7 +1114,7 @@ static int tipc_nl_compat_recv(struct sk_buff *skb, struct genl_info *info)
         }
 
         len = nlmsg_attrlen(req_nlh, GENL_HDRLEN + TIPC_GENL_HDRLEN);
-        if (TLV_GET_LEN(msg.req) && !TLV_OK(msg.req, len)) {
+        if (len && !TLV_OK(msg.req, len)) {
                 msg.rep = tipc_get_err_tlv(TIPC_CFG_NOT_SUPPORTED);
                 err = -EOPNOTSUPP;
                 goto send;