From: Richard Alpe <richard.alpe@ericsson.com>
Date: Mon, 17 Aug 2015 12:15:10 +0000 (+0200)
Subject: tipc: don't sanity check non-existing TLV (NL compat)
X-Git-Tag: v4.3-rc1~96^2~162
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=8f8ff9135b28a7560a5627aceaf289e3f0d4cd64;p=karo-tx-linux.git

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>
---

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;