From: Linus Torvalds <torvalds@linux-foundation.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <peterz@infradead.org>,
Darren Hart <dvhltc@us.ibm.com>
Subject: Re: [PATCH V2] futex: Fix the write access fault problem for real
Date: Wed, 24 Jun 2009 09:46:59 -0700 (PDT) [thread overview]
Message-ID: <alpine.LFD.2.01.0906240946000.3240@localhost.localdomain> (raw)
In-Reply-To: <alpine.LFD.2.00.0906241629590.2767@localhost.localdomain>
On Wed, 24 Jun 2009, Thomas Gleixner wrote:
>
> The solution is to not rely on access_ok and get_user() for any write
> access related fault on private and shared futexes. Instead we need to
> fault it in with verification of write access.
>
> There is no generic non destructive write mechanism which would fault
> the user page in trough a #PF, but as we already know that we will
> fault we can as well call get_user_pages() directly and avoid the #PF
> overhead.
Ack. Patch looks saner this way, and the commit message explains the
issues.
Linus
next prev parent reply other threads:[~2009-06-24 16:48 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-24 14:36 Thomas Gleixner
2009-06-24 16:46 ` Linus Torvalds [this message]
2009-06-24 19:48 ` [GIT pull] futex fixes for 2.6.31 Thomas Gleixner
2009-06-25 2:43 ` Zhang, Yanmin
2009-06-25 9:56 ` Thomas Gleixner
2009-06-25 10:04 ` Ingo Molnar
2009-06-25 18:15 ` [GIT pull] final " Thomas Gleixner
2009-06-25 18:26 ` Linus Torvalds
2009-06-25 9:58 ` [PATCH] clarify get_user_pages() prototype Peter Zijlstra
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