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

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Message-ID: <1382017117.2045.146.camel@edumazet-glaptop.roam.corp.google.com>
Date:	Thu, 17 Oct 2013 06:38:37 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Michal Kubecek <mkubecek@...e.cz>
Cc:	Steffen Klassert <steffen.klassert@...unet.com>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH ipsec v3] xfrm: prevent ipcomp scratch buffer race
 condition

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>



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