netdev - Re: [PATCH ipsec v3] xfrm: prevent ipcomp scratch buffer race condition

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Message-ID: <20131017133958.GA22197@gondor.apana.org.au>
Date:	Thu, 17 Oct 2013 21:39:59 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Michal Kubecek <mkubecek@...e.cz>,
	Steffen Klassert <steffen.klassert@...unet.com>,
	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH ipsec v3] xfrm: prevent ipcomp scratch buffer race
 condition

On Thu, Oct 17, 2013 at 06:38:37AM -0700, Eric Dumazet wrote:
> On Thu, 2013-10-17 at 15:07 +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.
> > 
> > v2: as pointed out by Steffen Klassert, if we also move the
> > local_bh_disable() before reading the per-cpu pointers, we can
> > get rid of get_cpu()/put_cpu().
> > 
> > v3: removed ipcomp_decompress part (as explained by Herbert Xu,
> > it cannot be called from process context), get rid of cpu
> > variable (thanks to Eric Dumazet)
> > 
> > Signed-off-by: Michal Kubecek <mkubecek@...e.cz>
> > ---
> 
> Reviewed-by: Eric Dumazet <edumazet@...gle.com>

Acked-by: Herbert Xu <herbert@...dor.apana.org.au>

Thanks,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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