linux-kernel - Re: [PATCH v2] sched: check user input value of sysctl_sched_time

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Message-ID: <20170906195027.GK29261@wotan.suse.de>
Date:   Wed, 6 Sep 2017 21:50:27 +0200
From:   "Luis R. Rodriguez" <mcgrof@...nel.org>
To:     Ethan Zhao <ethan.zhao@...cle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>, mingo@...hat.com,
        mcgrof@...nel.org, keescook@...omium.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        james.puthukattukaran@...cle.com, ethan.kernel@...il.com
Subject: Re: [PATCH v2] sched: check user input value of sysctl_sched_time_avg

On Mon, Sep 04, 2017 at 03:54:23PM +0800, Ethan Zhao wrote:
> Peter,
> 
> 
> On 2017/9/4 15:49, Peter Zijlstra wrote:
> > On Sat, Sep 02, 2017 at 02:57:32PM +0800, Ethan Zhao wrote:
> > > diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> > > index 6648fbb..609bed2 100644
> > > --- a/kernel/sysctl.c
> > > +++ b/kernel/sysctl.c
> > > @@ -367,7 +367,7 @@ static int sysrq_sysctl_handler(struct ctl_table *table, int write,
> > >   		.data		= &sysctl_sched_time_avg,
> > >   		.maxlen		= sizeof(unsigned int),
> > >   		.mode		= 0644,
> > > -		.proc_handler	= proc_dointvec,
> > > +		.proc_handler	= sched_time_avg_handler,
> > *sigh*, what's wrong with the below? Too easy?
>  :),  seems I walked zigzag several cycles to get the right point.

It sounds like negative values are not possible too, right? If so then
you can use proc_douintvec_minmax().

  Luis