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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20131015094603.GX7660@secunet.com>
Date:	Tue, 15 Oct 2013 11:46:03 +0200
From:	Steffen Klassert <steffen.klassert@...unet.com>
To:	Fan Du <fan.du@...driver.com>
Cc:	Michal Kubecek <mkubecek@...e.cz>,
	Herbert Xu <herbert@...dor.hengli.com.au>,
	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition

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.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html