From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755469AbcKNDlr (ORCPT ); Sun, 13 Nov 2016 22:41:47 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:45275 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752824AbcKNCER (ORCPT ); Sun, 13 Nov 2016 21:04:17 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "David S. Miller" , "Herbert Xu" Date: Mon, 14 Nov 2016 00:14:20 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 003/346] macvlan: Fix potential use-after free for broadcasts In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.39-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Herbert Xu commit 260916dfb48c374f7840f3b86e69afd3afdb6e96 upstream. When we postpone a broadcast packet we save the source port in the skb if it is local. However, the source port can disappear before we get a chance to process the packet. This patch fixes this by holding a ref count on the netdev. It also delays the skb->cb modification until after we allocate the new skb as you should not modify shared skbs. Fixes: 412ca1550cbe ("macvlan: Move broadcasts into a work queue") Signed-off-by: Herbert Xu Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- drivers/net/macvlan.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/drivers/net/macvlan.c +++ b/drivers/net/macvlan.c @@ -234,11 +234,14 @@ static void macvlan_process_broadcast(st rcu_read_unlock(); + if (src) + dev_put(src->dev); kfree_skb(skb); } } static void macvlan_broadcast_enqueue(struct macvlan_port *port, + const struct macvlan_dev *src, struct sk_buff *skb) { struct sk_buff *nskb; @@ -248,8 +251,12 @@ static void macvlan_broadcast_enqueue(st if (!nskb) goto err; + MACVLAN_SKB_CB(nskb)->src = src; + spin_lock(&port->bc_queue.lock); if (skb_queue_len(&port->bc_queue) < MACVLAN_BC_QUEUE_LEN) { + if (src) + dev_hold(src->dev); __skb_queue_tail(&port->bc_queue, nskb); err = 0; } @@ -296,8 +303,7 @@ static rx_handler_result_t macvlan_handl goto out; } - MACVLAN_SKB_CB(skb)->src = src; - macvlan_broadcast_enqueue(port, skb); + macvlan_broadcast_enqueue(port, src, skb); return RX_HANDLER_PASS; }