linux-kernel - Re: [PATCH v2] sysctl: handle table->maxlen properly for proc

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Date:   Wed, 25 May 2022 14:27:46 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     Luis Chamberlain <mcgrof@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Matthew Wilcox <willy@...radead.org>,
        Kees Cook <keescook@...omium.org>,
        Iurii Zaikin <yzaikin@...gle.com>
Subject: Re: [PATCH v2] sysctl: handle table->maxlen properly for proc_dobool

On Wed, May 25, 2022 at 12:20 AM Luis Chamberlain <mcgrof@...nel.org> wrote:
>
> On Tue, May 24, 2022 at 10:30:01AM +0800, Muchun Song wrote:
> > On Tue, May 24, 2022 at 1:27 AM Luis Chamberlain <mcgrof@...nel.org> wrote:
> > >
> > > On Sun, May 22, 2022 at 01:26:24PM +0800, Muchun Song wrote:
> > > > Setting ->proc_handler to proc_dobool at the same time setting ->maxlen
> > > > to sizeof(int) is counter-intuitive, it is easy to make mistakes.  For
> > > > robustness, fix it by reimplementing proc_dobool() properly.
> > > >
> > > > Signed-off-by: Muchun Song <songmuchun@...edance.com>
> > > > Cc: Luis Chamberlain <mcgrof@...nel.org>
> > > > Cc: Kees Cook <keescook@...omium.org>
> > > > Cc: Iurii Zaikin <yzaikin@...gle.com>
> > > > ---
> > >
> > > Thanks for your patch Muchun!
> > >
> > > Does this fix an actualy issue? Because the comit log suggest so.
> >
> > Thanks for taking a look.
> >
> > I think it is an improvement not a real bug fix.
>
> Then please adjust the commit log accordingly.
>
> > When I first use
> > proc_dobool in my driver, I assign sizeof(variable) to table->maxlen.
> > Then I found it was wrong, it should be sizeof(int) which was
> > counter-intuitive. So it is very easy to make mistakes. Should I add
> > those into the commit log?
>
> Yes that is useful information when doing patch review as well.
>

Thanks. I'll update in v3.