From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754819AbbLIJlZ (ORCPT ); Wed, 9 Dec 2015 04:41:25 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:45450 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754792AbbLIJlU (ORCPT ); Wed, 9 Dec 2015 04:41:20 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Eric Dumazet , Willem de Bruijn , Eric Leblond , "David S. Miller" , Luis Henriques Subject: [PATCH 3.16.y-ckt 095/126] packet: fix match_fanout_group() Date: Wed, 9 Dec 2015 09:37:45 +0000 Message-Id: <1449653896-5236-96-git-send-email-luis.henriques@canonical.com> In-Reply-To: <1449653896-5236-1-git-send-email-luis.henriques@canonical.com> References: <1449653896-5236-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.7-ckt21 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit 161642e24fee40fba2c5bc2ceacc00d118a22d65 upstream. Recent TCP listener patches exposed a prior af_packet bug : match_fanout_group() blindly assumes it is always safe to cast sk to a packet socket to compare fanout with af_packet_priv But SYNACK packets can be sent while attached to request_sock, which are smaller than a "struct sock". We can read non existent memory and crash. Fixes: c0de08d04215 ("af_packet: don't emit packet on orig fanout group") Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener") Signed-off-by: Eric Dumazet Cc: Willem de Bruijn Cc: Eric Leblond Signed-off-by: David S. Miller Signed-off-by: Luis Henriques --- net/packet/af_packet.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index e6bd6df9e2a2..1f618bbce0ac 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1412,10 +1412,10 @@ static void __fanout_unlink(struct sock *sk, struct packet_sock *po) static bool match_fanout_group(struct packet_type *ptype, struct sock *sk) { - if (ptype->af_packet_priv == (void *)((struct packet_sock *)sk)->fanout) - return true; + if (sk->sk_family != PF_PACKET) + return false; - return false; + return ptype->af_packet_priv == pkt_sk(sk)->fanout; } static int fanout_add(struct sock *sk, u16 id, u16 type_flags)