linux-kernel - Re: Kernel oops with 2.6.26, padlock and ipsec: probably problem with fpu state changes

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]

Date:	Sat, 09 Aug 2008 09:05:50 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Herbert Xu <herbert@...dor.apana.org.au>
CC:	Suresh Siddha <suresh.b.siddha@...el.com>,
	Wolfgang Walter <wolfgang.walter@...m.de>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>,
	"viro@...IV.linux.org.uk" <viro@...IV.linux.org.uk>,
	"vegard.nossum@...il.com" <vegard.nossum@...il.com>
Subject: Re: Kernel oops with 2.6.26, padlock and ipsec: probably problem
 with fpu state changes

Herbert Xu wrote:
> On Fri, Aug 08, 2008 at 04:11:21PM -0700, Suresh Siddha wrote:
>> With out the recent dynamic fpu allocation changes, while we don't see oops,
>> there is a possible race still present in older kernels(for example,
>> while kernel is using kernel_fpu_begin() in some optimized clear/copy
>> page and an interrupt/softirq happens which uses these padlock
>> instructions generating DNA fault).
> 
> No this wasn't a problem because kernel_fpu_begin clears TS and
> therefore we don't get faults on SSE instructions.
> 
> However, with your patch it will become a problem due to the
> fact that it wasn't designed to be nested.
> 

We're invoking this code from interrupt handlers?

	-hpa

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/