From: Steffen Klassert <steffen.klassert@secunet•com>
To: Michal Kubecek <mkubecek@suse•cz>
Cc: Herbert Xu <herbert@gondor•apana.org.au>,
"David S. Miller" <davem@davemloft•net>,
netdev@vger•kernel.org
Subject: Re: [PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition
Date: Tue, 15 Oct 2013 10:33:48 +0200 [thread overview]
Message-ID: <20131015083348.GW7660@secunet.com> (raw)
In-Reply-To: <20131014160334.BCCDDE8A31@unicorn.suse.cz>
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.
>
> Add similar protection into ipcomp_decompress() as it can be
> called from process context as well (even if such scenario seems
> a bit artificial).
>
> Signed-off-by: Michal Kubecek <mkubecek@suse•cz>
> ---
> net/xfrm/xfrm_ipcomp.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
> index 2906d52..96946fb 100644
> --- a/net/xfrm/xfrm_ipcomp.c
> +++ b/net/xfrm/xfrm_ipcomp.c
> @@ -48,9 +48,11 @@ static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
> const int cpu = get_cpu();
> u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
> struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
> - int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
> + int err;
> int len;
>
> + local_bh_disable();
Maybe we could disable the BHs before we fetch the percpu pointers.
Then we can use smp_processor_id() to get the cpu. With that we
could get rid of a (now useless) preempt_disable()/preempt_enable()
pair. Same could be done in ipcomp_compress().
Looks ok otherwise. Thanks!
next prev parent reply other threads:[~2013-10-15 8:33 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-14 16:03 [PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition Michal Kubecek
2013-10-15 8:33 ` Steffen Klassert [this message]
2013-10-15 8:59 ` Fan Du
2013-10-15 9:46 ` Steffen Klassert
2013-10-15 20:55 ` Michal Kubecek
2013-10-15 21:40 ` [PATCH ipsec v2] " Michal Kubecek
2013-10-15 22:44 ` Eric Dumazet
2013-10-16 12:32 ` [PATCH ipsec] " Herbert Xu
2013-10-17 9:55 ` Steffen Klassert
2013-10-17 13:07 ` [PATCH ipsec v3] " Michal Kubecek
2013-10-17 13:38 ` Eric Dumazet
2013-10-17 13:39 ` Herbert Xu
2013-10-18 9:25 ` Steffen Klassert
2013-10-18 10:54 ` [PATCH ipsec-next] xfrm: use vmalloc_node() for percpu scratches Eric Dumazet
2013-10-18 12:46 ` Herbert Xu
2013-10-21 14:48 ` Steffen Klassert
2013-10-17 11:01 ` [PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition Michal Kubecek
2013-10-17 11:04 ` Herbert Xu
2013-10-17 13:13 ` Michal Kubecek
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