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

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Message-ID: <Yo0FzkTJj2TrLtTO@bombadil.infradead.org>
Date:   Tue, 24 May 2022 09:20:30 -0700
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Muchun Song <songmuchun@...edance.com>
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 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.

  Luis