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Message-Id: <20200526183922.661550701@linuxfoundation.org>
Date: Tue, 26 May 2020 20:53:07 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org, greg@...ah.com
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Guillaume Nault <g.nault@...halink.fr>,
"David S. Miller" <davem@...emloft.net>,
Giuliano Procida <gprocida@...gle.com>
Subject: [PATCH 4.4 48/65] l2tp: initialise sessions refcount before making it reachable
From: Guillaume Nault <g.nault@...halink.fr>
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 <g.nault@...halink.fr>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Giuliano Procida <gprocida@...gle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
net/l2tp/l2tp_core.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -1853,6 +1853,8 @@ struct l2tp_session *l2tp_session_create
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
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 */
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