linux-kernel - Re: [PATCH 1/4] cpumask: Migrate 'alloc_cpumask_var()' users to 'zalloc_cpumask

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: <20151208040903.GA31689@gmail.com>
Date:	Tue, 8 Dec 2015 05:09:03 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Peter Zijlstra <peterz@...radead.org>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Xunlei Pang <xlpang@...hat.com>,
	Rik van Riel <riel@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 1/4] cpumask: Migrate 'alloc_cpumask_var()' users to
 'zalloc_cpumask_var()'


* Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> On Mon, Dec 7, 2015 at 12:49 AM, Ingo Molnar <mingo@...nel.org> wrote:
> > Xunlei Pang reported a scheduler bug in init_rootdomain(), which is
> > caused by improper use of alloc_cpumask_var(), which results in
> > uninitialized cpumasks being allocated.
> >
> > No-one noticed this scheduler bug for a long time, probably because
> > alloc_cpumask_var() does result in initialized cpumasks in the
> > !CPUMASK_OFFSTACK case - which is the vast majority of systems
> > out there.
> >
> > So migrate all alloc_cpumask_var() users over to zalloc_cpumask_var(), to be 
> > on the safe side.
> 
> Ugh. I'd rather just see us say that "allocating a cpumask always returns a 
> zeroed mask".
> 
> There really is no reason to ever not zero it (they aren't _that_ big even on 
> huge machines), so I'd rather just get rid of the "zalloc" version that is the 
> less common one anyway.

Sure - that was my original suggestion, will reshape the series to do it like 
that.

Thanks,

	Ingo
--
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/