From df9fdbc23b7facbbaab468e7f3d8b7e6a10aaee1 Mon Sep 17 00:00:00 2001 From: Guillaume Nault Date: Fri, 22 May 2020 00:57:28 +0100 Subject: l2tp: initialise session's refcount before making it reachable commit 9ee369a405c57613d7c83a3967780c3e30c52ecc upstream. 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. Backporting Notes l2tp_core.c: moving code that had been converted from atomic to refcount_t by an earlier change (which isn't being included in this patch series). Fixes: dbdbc73b4478 ("l2tp: fix duplicate session creation") Signed-off-by: Guillaume Nault Signed-off-by: David S. Miller Signed-off-by: Giuliano Procida Signed-off-by: Greg Kroah-Hartman --- 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 7e593e399774..c0abd5efd824 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -1853,6 +1853,8 @@ struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunn l2tp_session_set_header_len(session, tunnel->version); + l2tp_session_inc_refcount(session); + err = l2tp_session_add_to_tunnel(tunnel, session); if (err) { kfree(session); @@ -1860,10 +1862,6 @@ 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. - */ - l2tp_session_inc_refcount(session); l2tp_tunnel_inc_refcount(tunnel); /* Ensure tunnel socket isn't deleted */ -- cgit v1.2.3