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

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Message-ID: <1465310395.29158.2.camel@redhat.com>
Date:	Tue, 07 Jun 2016 09:39:55 -0500
From:	Dan Williams <dcbw@...hat.com>
To:	Pavel Andrianov <andrianov@...ras.ru>,
	Kalle Valo <kvalo@...eaurora.org>
Cc:	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, 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?

Dan