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

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Date:	Tue, 14 Jun 2016 17:16:11 +0400
From:	Pavel Andrianov <andrianov@...ras.ru>
To:	James Cameron <quozl@...top.org>
CC:	Dan Williams <dcbw@...hat.com>, 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

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@...ras.ru


View attachment "0001-libertas-Add-spinlock-to-avoid-race-condition.patch" of type "text/x-patch" (1330 bytes)