linux-kernel - Re: [PATCH -v8 3/4] Enable the MS_ASYNC functionality in sys

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: <1201200973.3897.31.camel@cinder.waste.org>
Date:	Thu, 24 Jan 2008 12:56:13 -0600
From:	Matt Mackall <mpm@...enic.com>
To:	Nick Piggin <nickpiggin@...oo.com.au>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Anton Salikhmetov <salikhmetov@...il.com>, linux-mm@...ck.org,
	jakob@...hought.net, linux-kernel@...r.kernel.org,
	valdis.kletnieks@...edu, riel@...hat.com, ksm@...dk,
	staubach@...hat.com, jesper.juhl@...il.com, a.p.zijlstra@...llo.nl,
	akpm@...ux-foundation.org, protasnb@...il.com, miklos@...redi.hu,
	r.e.wolff@...wizard.nl, hidave.darkstar@...il.com,
	hch@...radead.org
Subject: Re: [PATCH -v8 3/4] Enable the MS_ASYNC functionality in
	sys_msync()


On Thu, 2008-01-24 at 12:36 +1100, Nick Piggin wrote:
> On Thursday 24 January 2008 04:05, Linus Torvalds wrote:
> > On Wed, 23 Jan 2008, Anton Salikhmetov wrote:
> > > +
> > > +		if (pte_dirty(*pte) && pte_write(*pte)) {
> >
> > Not correct.
> >
> > You still need to check "pte_present()" before you can test any other
> > bits. For a non-present pte, none of the other bits are defined, and for
> > all we know there might be architectures out there that require them to
> > be non-dirty.
> >
> > As it is, you just possibly randomly corrupted the pte.
> >
> > Yeah, on all architectures I know of, it the pte is clear, neither of
> > those tests will trigger, so it just happens to work, but it's still
> > wrong.
> 
> Probably it can fail for !present nonlinear mappings on many
> architectures.

Definitely.

-- 
Mathematics is the supreme nostalgia of our time.

--
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/