netdev - Re: [PATCH v2 3/3] pppoatm: protect against freeing of vcc

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Message-ID: <1354240620.21562.256.camel@shinybook.infradead.org>
Date:	Fri, 30 Nov 2012 01:57:00 +0000
From:	David Woodhouse <dwmw2@...radead.org>
To:	"Chas Williams (CONTRACTOR)" <chas@....nrl.navy.mil>
Cc:	Krzysztof Mazur <krzysiek@...lesie.net>,
	David Laight <David.Laight@...LAB.COM>, davem@...emloft.net,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	nathan@...verse.com.au
Subject: Re: [PATCH v2 3/3] pppoatm: protect against freeing of vcc

On Thu, 2012-11-29 at 20:38 -0500, Chas Williams (CONTRACTOR) wrote:
> it isnt clear to me that fixes the race entirely either.
> vcc_destroy_socket() and any of the push()/sends()'s are not
> serialized.
> while you may clear the ATM_VF_READY flag, you might not clear it soon
> enough for any particular push() that is already running.  so it still
> seems like you are racing close() against push() at this point.  the
> window is greatly reduced, but it still exists.

I think it's actually fixed for pppoatm by the bh_lock_sock() and the
sock_owned_by_user() check. As soon as vcc_release() calls lock_sock(),
pppoatm stops accepting packets.

It should be simple enough to do the same in br2684.

-- 
dwmw2


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