linux-kernel - [PATCH 4.9 49/74] l2tp: check sockaddr length in pppol2tp

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Message-Id: <20180427135711.964602787@linuxfoundation.org>
Date:   Fri, 27 Apr 2018 15:58:39 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+a70ac890b23b1bf29f5c@...kaller.appspotmail.com,
        Guillaume Nault <g.nault@...halink.fr>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.9 49/74] l2tp: check sockaddr length in pppol2tp_connect()

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

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


[ Upstream commit eb1c28c05894a4b1f6b56c5bf072205e64cfa280 ]

Check sockaddr_len before dereferencing sp->sa_protocol, to ensure that
it actually points to valid data.

Fixes: fd558d186df2 ("l2tp: Split pppol2tp patch into separate l2tp and ppp parts")
Reported-by: syzbot+a70ac890b23b1bf29f5c@...kaller.appspotmail.com
Signed-off-by: Guillaume Nault <g.nault@...halink.fr>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/l2tp/l2tp_ppp.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -590,6 +590,13 @@ static int pppol2tp_connect(struct socke
 	lock_sock(sk);
 
 	error = -EINVAL;
+
+	if (sockaddr_len != sizeof(struct sockaddr_pppol2tp) &&
+	    sockaddr_len != sizeof(struct sockaddr_pppol2tpv3) &&
+	    sockaddr_len != sizeof(struct sockaddr_pppol2tpin6) &&
+	    sockaddr_len != sizeof(struct sockaddr_pppol2tpv3in6))
+		goto end;
+
 	if (sp->sa_protocol != PX_PROTO_OL2TP)
 		goto end;