netdev - Re: [PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition

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Message-ID: <20131017095502.GD7660@secunet.com>
Date:	Thu, 17 Oct 2013 11:55:02 +0200
From:	Steffen Klassert <steffen.klassert@...unet.com>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	Michal Kubecek <mkubecek@...e.cz>,
	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition

On Wed, Oct 16, 2013 at 08:32:05PM +0800, Herbert Xu wrote:
> On Mon, Oct 14, 2013 at 06:03:34PM +0200, Michal Kubecek wrote:
> > In ipcomp_compress(), sortirq is enabled too early, allowing the
> > per-cpu scratch buffer to be rewritten by ipcomp_decompress()
> > (called on the same CPU in softirq context) between populating
> > the buffer and copying the compressed data to the skb.
> 
> Good catch.
> 
> > Add similar protection into ipcomp_decompress() as it can be
> > called from process context as well (even if such scenario seems
> > a bit artificial).
> 
> I don't think this is possible or otherwise xfrm_input will
> dead-lock.
> 

Michal, please incorporate the feedback from Herbert and Eric,
I'll take it into the ipsec tree then. Thanks!
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