netdev - Re: [ldv-project] [net] libertas: potential race condition

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Date:	Wed, 8 Jun 2016 08:51:14 +1000
From:	James Cameron <quozl@...top.org>
To:	Dan Williams <dcbw@...hat.com>
Cc:	Pavel Andrianov <andrianov@...ras.ru>,
	Kalle Valo <kvalo@...eaurora.org>,
	libertas-dev@...ts.infradead.org, LDV list <ldv-project@...ras.ru>,
	netdev@...r.kernel.org, linux-wireless@...r.kernel.org,
	linux-kernel@...r.kernel.org, vaishali.thakkar@...cle.com
Subject: Re: [ldv-project] [net] libertas: potential race condition

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).

-- 
James Cameron
http://quozl.netrek.org/