path: root/net
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authorGuillaume Nault <g.nault@alphalink.fr>2018-06-13 15:09:19 +0200
committerDavid S. Miller <davem@davemloft.net>2018-06-14 17:10:19 -0700
commit7ac6ab1f8a38ba7f8d97f95475bb6a2575db4658 (patch)
tree1f554212a69107c536ef0cb58180deed08be415d /net
parent90904ff5f958a215cc3d26f957a46e80fa178470 (diff)
l2tp: only accept PPP sessions in pppol2tp_connect()
l2tp_session_priv() returns a struct pppol2tp_session pointer only for PPPoL2TP sessions. In particular, if the session is an L2TP_PWTYPE_ETH pseudo-wire, l2tp_session_priv() returns a pointer to an l2tp_eth_sess structure, which is much smaller than struct pppol2tp_session. This leads to invalid memory dereference when trying to lock ps->sk_lock. Fixes: d9e31d17ceba ("l2tp: Add L2TP ethernet pseudowire support") Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
1 files changed, 6 insertions, 0 deletions
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index 270a0a999eaf..8b3b6947a07d 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -734,6 +734,12 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
session = l2tp_session_get(sock_net(sk), tunnel, session_id);
if (session) {
drop_refcnt = true;
+ if (session->pwtype != L2TP_PWTYPE_PPP) {
+ error = -EPROTOTYPE;
+ goto end;
+ }
ps = l2tp_session_priv(session);
/* Using a pre-existing session is fine as long as it hasn't

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