Commit 11a08372 authored May 22, 2020 by Guillaume Nault Committed by Greg Kroah-Hartman May 27, 2020

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 <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Giuliano Procida <gprocida@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent d4504d1e

net/l2tp/l2tp_core.c

+2 −4

Original line number	Diff line number	Diff line
		@@ -1847,6 +1847,8 @@ 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);
		@@ -1854,10 +1856,6 @@ 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 */