From: Steffen Klassert <steffen.klassert@secunet.com>
To: Fan Du <fan.du@windriver.com>
Cc: Michal Kubecek <mkubecek@suse.cz>,
Herbert Xu <herbert@gondor.hengli.com.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 11:46:03 +0200 [thread overview]
Message-ID: <20131015094603.GX7660@secunet.com> (raw)
In-Reply-To: <525D03D8.7060802@windriver.com>
On Tue, Oct 15, 2013 at 04:59:04PM +0800, Fan Du wrote:
>
>
> On 2013年10月15日 16:33, Steffen Klassert wrote:
> >
> >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().
>
> Is it possible that two tasks race scratch buffer when both of them trying to compress data
> without preempt disabled? for example, when task A working on compression, then task B
> with higher priority preempts task A, and try to touch scratch buffer, which leaves stale
> data for task A after then.
>
> I think we needs preempt disabled for such case, otherwise I overlook codes in somewhere else.
>
You overlook that preemption is disabled if the BHs are disabled.
next prev parent reply other threads:[~2013-10-15 9:46 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
2013-10-15 8:59 ` Fan Du
2013-10-15 9:46 ` Steffen Klassert [this message]
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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