netdev - [PATCH] net/x25: Fix null-ptr-deref in x25

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Date:   Mon, 28 Sep 2020 11:23:27 +0200
From:   Martin Schiller <ms@....tdt.de>
To:     andrew.hendry@...il.com, davem@...emloft.net, kuba@...nel.org,
        edumazet@...gle.com, xiyuyang19@...an.edu.cn
Cc:     linux-x25@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Martin Schiller <ms@....tdt.de>
Subject: [PATCH] net/x25: Fix null-ptr-deref in x25_connect

This fixes a regression for blocking connects introduced by commit
4becb7ee5b3d ("net/x25: Fix x25_neigh refcnt leak when x25 disconnect").

The x25->neighbour is already set to "NULL" by x25_disconnect() now,
while a blocking connect is waiting in
x25_wait_for_connection_establishment(). Therefore x25->neighbour must
not be accessed here again and x25->state is also already set to
X25_STATE_0 by x25_disconnect().

Fixes: 4becb7ee5b3d ("net/x25: Fix x25_neigh refcnt leak when x25 disconnect")
Signed-off-by: Martin Schiller <ms@....tdt.de>
---
 net/x25/af_x25.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
index 0bbb283f23c9..0524a5530b91 100644
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -820,7 +820,7 @@ static int x25_connect(struct socket *sock, struct sockaddr *uaddr,
 
 	rc = x25_wait_for_connection_establishment(sk);
 	if (rc)
-		goto out_put_neigh;
+		goto out;
 
 	sock->state = SS_CONNECTED;
 	rc = 0;
-- 
2.20.1