linux-kernel - [PATCH 4.9 32/64] l2tp: remove useless duplicate session detection in l2tp

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Date:   Tue, 26 May 2020 20:53:01 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org, greg@...ah.com
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Guillaume Nault <g.nault@...halink.fr>,
        "David S. Miller" <davem@...emloft.net>,
        Giuliano Procida <gprocida@...gle.com>
Subject: [PATCH 4.9 32/64] l2tp: remove useless duplicate session detection in l2tp_netlink

From: Guillaume Nault <g.nault@...halink.fr>

commit af87ae465abdc070de0dc35d6c6a9e7a8cd82987 upstream.

There's no point in checking for duplicate sessions at the beginning of
l2tp_nl_cmd_session_create(); the ->session_create() callbacks already
return -EEXIST when the session already exists.

Furthermore, even if l2tp_session_find() returns NULL, a new session
might be created right after the test. So relying on ->session_create()
to avoid duplicate session is the only sane behaviour.

Signed-off-by: Guillaume Nault <g.nault@...halink.fr>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Giuliano Procida <gprocida@...gle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/l2tp/l2tp_netlink.c |    5 -----
 1 file changed, 5 deletions(-)

--- a/net/l2tp/l2tp_netlink.c
+++ b/net/l2tp/l2tp_netlink.c
@@ -513,11 +513,6 @@ static int l2tp_nl_cmd_session_create(st
 		goto out;
 	}
 	session_id = nla_get_u32(info->attrs[L2TP_ATTR_SESSION_ID]);
-	session = l2tp_session_find(net, tunnel, session_id);
-	if (session) {
-		ret = -EEXIST;
-		goto out;
-	}
 
 	if (!info->attrs[L2TP_ATTR_PEER_SESSION_ID]) {
 		ret = -EINVAL;