Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932725AbdGCNnz (ORCPT ); Mon, 3 Jul 2017 09:43:55 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:36384 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932667AbdGCNnm (ORCPT ); Mon, 3 Jul 2017 09:43:42 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Guillaume Nault , "David S. Miller" , Amit Pundir Subject: [PATCH 4.9 046/172] l2tp: ensure session cant get removed during pppol2tp_session_ioctl() Date: Mon, 3 Jul 2017 15:33:46 +0200 Message-Id: <20170703133416.392837936@linuxfoundation.org> X-Mailer: git-send-email 2.13.2 In-Reply-To: <20170703133414.260777365@linuxfoundation.org> References: <20170703133414.260777365@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1593 Lines: 49 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Guillaume Nault commit 57377d63547861919ee634b845c7caa38de4a452 upstream. Holding a reference on session is required before calling pppol2tp_session_ioctl(). The session could get freed while processing the ioctl otherwise. Since pppol2tp_session_ioctl() uses the session's socket, we also need to take a reference on it in l2tp_session_get(). Fixes: fd558d186df2 ("l2tp: Split pppol2tp patch into separate l2tp and ppp parts") Signed-off-by: Guillaume Nault Signed-off-by: David S. Miller Signed-off-by: Amit Pundir Signed-off-by: Greg Kroah-Hartman --- net/l2tp/l2tp_ppp.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) --- a/net/l2tp/l2tp_ppp.c +++ b/net/l2tp/l2tp_ppp.c @@ -1141,11 +1141,18 @@ static int pppol2tp_tunnel_ioctl(struct if (stats.session_id != 0) { /* resend to session ioctl handler */ struct l2tp_session *session = - l2tp_session_find(sock_net(sk), tunnel, stats.session_id); - if (session != NULL) - err = pppol2tp_session_ioctl(session, cmd, arg); - else + l2tp_session_get(sock_net(sk), tunnel, + stats.session_id, true); + + if (session) { + err = pppol2tp_session_ioctl(session, cmd, + arg); + if (session->deref) + session->deref(session); + l2tp_session_dec_refcount(session); + } else { err = -EBADR; + } break; } #ifdef CONFIG_XFRM