linux-kernel - Re: [PATCH] Set bounds on what /proc/self/make-it-fail accepts.

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Date:	Wed, 19 Feb 2014 22:48:21 +0900
From:	Akinobu Mita <akinobu.mita@...il.com>
To:	Dave Jones <davej@...hat.com>,
	David Rientjes <rientjes@...gle.com>,
	Akinobu Mita <akinobu.mita@...il.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH] Set bounds on what /proc/self/make-it-fail accepts.

2014-02-19 8:27 GMT+09:00 Dave Jones <davej@...hat.com>:
> On Tue, Feb 18, 2014 at 02:32:02PM -0800, David Rientjes wrote:
>  > On Tue, 18 Feb 2014, Dave Jones wrote:
>  >
>  > > /proc/self/make-it-fail is a boolean, but accepts any number, including
>  > > negative ones. Change variable to unsigned, and cap upper bound at 1.
>  >
>  > Hmm, this would break anything that uses anything other than one to enable
>  > it, but it looks like Documentation/fault-injection/fault-injection.txt
>  > only provides an example for when it does equal one, so it's probably an
>  > ok change.  I'm just wondering why non-zero is wrong?  Is this an
>  > interface that will be extended to support other modes?
>
> "Wrong" is perhaps too strong a word, but we only ever check it for non-zero state,
> so it seems at best suboptimal to allow strange configurations.
>
> When I saw I could set it to nonsense values like -1, I figured it could
> use some idiot proofing. The lack of any checking at all surprised me.
>
> Future extension of this interface seems unlikely given the boolean sounding name.
> (Though we've done that in the past with things like the overcommit_memory sysctl,
>  with pretty awful end-user results).

I don't have any plans to extend /proc/self/make-it-fail to support
other than 0 or 1.  So I have no objection against this change.

Reviewed-by: Akinobu Mita <akinobu.mita@...il.com>
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