netdev - [PATCH net-next] tipc: don't sanity check non-existing TLV (NL compat)

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Message-ID: <1439813710-11322-1-git-send-email-richard.alpe@ericsson.com>
Date:	Mon, 17 Aug 2015 14:15:10 +0200
From:	<richard.alpe@...csson.com>
To:	<netdev@...r.kernel.org>
CC:	<tipc-discussion@...ts.sourceforge.net>,
	Richard Alpe <richard.alpe@...csson.com>
Subject: [PATCH net-next] tipc: don't sanity check non-existing TLV (NL compat)

From: Richard Alpe <richard.alpe@...csson.com>

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@...csson.com>
Reviewed-by: Erik Hugne <erik.hugne@...csson.com>
---
 net/tipc/netlink_compat.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/tipc/netlink_compat.c b/net/tipc/netlink_compat.c
index 53e0fee..1eadc95 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;
-- 
2.1.4

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