From 9ee369a405c57613d7c83a3967780c3e30c52ecc Mon Sep 17 00:00:00 2001 From: Guillaume Nault Date: Fri, 25 Aug 2017 16:22:17 +0200 Subject: [PATCH] l2tp: initialise session's refcount before making it reachable Sessions must be fully initialised before calling l2tp_session_add_to_tunnel(). Otherwise, there's a short time frame where partially initialised sessions can be accessed by external users. Fixes: dbdbc73b4478 ("l2tp: fix duplicate session creation") Signed-off-by: Guillaume Nault Signed-off-by: David S. Miller --- net/l2tp/l2tp_core.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index b0c2d4ae781d..f363669eae47 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -1844,6 +1844,8 @@ struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunn l2tp_session_set_header_len(session, tunnel->version); + refcount_set(&session->ref_count, 1); + err = l2tp_session_add_to_tunnel(tunnel, session); if (err) { kfree(session); @@ -1851,10 +1853,6 @@ struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunn return ERR_PTR(err); } - /* Bump the reference count. The session context is deleted - * only when this drops to zero. - */ - refcount_set(&session->ref_count, 1); l2tp_tunnel_inc_refcount(tunnel); /* Ensure tunnel socket isn't deleted */ -- 2.20.1