linux-kernel - Re: [PATCH 3/5] lguest: avoid accidental recycling of pgdir pages

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: <49CCFE9C.6060702@goop.org>
Date:	Fri, 27 Mar 2009 09:28:12 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Rusty Russell <rusty@...tcorp.com.au>
CC:	lguest@...abs.org, Ingo Molnar <mingo@...hat.com>,
	linux-kernel@...r.kernel.org,
	virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH 3/5] lguest: avoid accidental recycling of pgdir pages

Rusty Russell wrote:
>> You can't just do this in tlb flush?
>>     
>
> I don't think so.  The problem is that lguest tracks 4 toplevels, using random
> replacement.  This cache is indexed by cr3 value.
>
> Lguest assumes it's told about all pte removals or changes, but simple
> additions get faulted in.  If a pgdir page gets reused we'll potentially have
> stale values from its previous life as a pgdir, no?
>   

Yes, but when you get a tlb flush hypercall, couldn't you also look up 
the corresponding shadow pte and zap it so that it will get repopulated 
next time around?  And a full tlb flush would just zap the entire 
shadow.  After all, the shadow pagetable is just a glorified 
software-managed tlb...

    J
--
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/