From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.ispras.ru ([83.149.199.45]:41973 "EHLO mail.ispras.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750762AbcFNOTw (ORCPT ); Tue, 14 Jun 2016 10:19:52 -0400 Message-ID: <5760039B.4050902@ispras.ru> (sfid-20160614_162042_356385_6B84EB1C) Date: Tue, 14 Jun 2016 17:16:11 +0400 From: Pavel Andrianov MIME-Version: 1.0 To: James Cameron CC: Dan Williams , Kalle Valo , libertas-dev@lists.infradead.org, LDV list , netdev@vger.kernel.org, linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, vaishali.thakkar@oracle.com Subject: Re: [ldv-project] [net] libertas: potential race condition References: <57569424.9040906@ispras.ru> <1465310395.29158.2.camel@redhat.com> <20160607225114.GA21437@us.netrek.org> In-Reply-To: <20160607225114.GA21437@us.netrek.org> Content-Type: multipart/mixed; boundary="------------020407090508040300010402" Sender: linux-wireless-owner@vger.kernel.org List-ID: This is a multi-part message in MIME format. --------------020407090508040300010402 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 08.06.2016 02:51, James Cameron пишет: > On Tue, Jun 07, 2016 at 09:39:55AM -0500, Dan Williams wrote: >> On Tue, 2016-06-07 at 13:30 +0400, Pavel Andrianov wrote: >>> Hi! >>> >>> There is a potential race condition in >>> drivers/net/wireless/libertas/libertas.ko. >>> In the function lbs_hard_start_xmit(..), line 159, a socket buffer >>> is >>> written to priv->current_skb with a spin_lock protection. >>> In the function lbs_mac_event_disconnected(..), lines 50-51, the >>> field >>> current_skb is cleaned. There is no protection used. The >>> corresponding >>> handlers are activated at the same time in lbs_start_card(..) and >>> then >>> may be executed simultaneously. Note, there are two structures >>> lbs_netdev_ops and mesh_netdev_ops, which have the target handler >>> lbs_hard_start_xmit. >>> Is it a real race or I have missed something? >> Yeah, it looks like it should be grabbing priv->driver_lock before >> clearing priv->currenttxskb in lbs_mac_event_disconnected(). Care to >> submit a patch after testing? Do you have any of that hardware? > I've hardware, with serial console. > > Can test any patch, on USB (8388) or SDIO (8686). > Hi! I've prepare the patch for this issue. Could you test it? Thank you. -- Pavel Andrianov Linux Verification Center, ISPRAS web: http://linuxtesting.org e-mail: andrianov@ispras.ru --------------020407090508040300010402 Content-Type: text/x-patch; name="0001-libertas-Add-spinlock-to-avoid-race-condition.patch" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="0001-libertas-Add-spinlock-to-avoid-race-condition.patch" >>From b1a9e157ccdf8650da93844fd2dbdb6fca509b59 Mon Sep 17 00:00:00 2001 From: Pavel Date: Tue, 14 Jun 2016 16:59:00 +0400 Subject: [PATCH] libertas: Add spinlock to avoid race condition lbs_mac_event_disconnected may free priv->currenttxskb while lbs_hard_start_xmit accesses to it. The patch adds a spinlock for mutual exclusion. Signed-off-by: Pavel --- drivers/net/wireless/marvell/libertas/cmdresp.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/net/wireless/marvell/libertas/cmdresp.c b/drivers/net/wireless/marvell/libertas/cmdresp.c index c95bf6d..c67ae07 100644 --- a/drivers/net/wireless/marvell/libertas/cmdresp.c +++ b/drivers/net/wireless/marvell/libertas/cmdresp.c @@ -27,6 +27,8 @@ void lbs_mac_event_disconnected(struct lbs_private *priv, bool locally_generated) { + unsigned long flags; + if (priv->connect_status != LBS_CONNECTED) return; @@ -46,9 +48,11 @@ void lbs_mac_event_disconnected(struct lbs_private *priv, netif_carrier_off(priv->dev); /* Free Tx and Rx packets */ + spin_lock_irqsave(&priv->driver_lock, flags); kfree_skb(priv->currenttxskb); priv->currenttxskb = NULL; priv->tx_pending_len = 0; + spin_unlock_irqrestore(&priv->driver_lock, flags); priv->connect_status = LBS_DISCONNECTED; -- 1.7.11.7 --------------020407090508040300010402--