linux-kernel - Re: [PATCH v5 2/4] kernel hacking: new config NO_AUTO_INLINE to disable compiler auto-inline optimizations

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Date:   Thu, 7 Jun 2018 11:18:16 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Bernd Petrovitsch <bernd@...rovitsch.priv.at>,
        "Du, Changbin" <changbin.du@...el.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        gregkh@...uxfoundation.org, alex.elder@...aro.org,
        Johan Hovold <johan@...nel.org>,
        kbuild test robot <lkp@...el.com>,
        linux-arch@...r.kernel.org, michal.lkml@...kovi.net,
        linux-kernel@...r.kernel.org, arnd@...db.de,
        yamada.masahiro@...ionext.com, lgirdwood@...il.com,
        broonie@...nel.org, rdunlap@...radead.org, x86@...nel.org,
        linux@...linux.org.uk, linux-sparse@...r.kernel.org,
        mingo@...hat.com, kbuild-all@...org, akpm@...ux-foundation.org,
        changbin.du@...il.com, tglx@...utronix.de,
        linux-kbuild@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v5 2/4] kernel hacking: new config NO_AUTO_INLINE to
 disable compiler auto-inline optimizations

On Thu, Jun 07, 2018 at 02:40:25PM +0530, Viresh Kumar wrote:
> On 07-06-18, 11:03, Bernd Petrovitsch wrote:
> > On Thu, 2018-06-07 at 14:08 +0530, Viresh Kumar wrote:
> > > On 07-06-18, 15:46, Du, Changbin wrote:
> > > > I think if the destination is not a null terminated string (If I understand your
> > > > description below), memcpy can be used to get rid of such warning. The warning
> > > > makes sense in general as explained in mannual. Thanks!
> > > 
> > > The destination should be a null terminated string eventually, but we first need
> > > to make sure src is a null terminated string.
> > 
> > Is there strnlen() or memchr() in the kernel?
> > Then check the source before copying it.
> 
> It would be extra work, but memchr can be used to work around this I believe.
> 
> @Johan ??

If you want to work around the warning and think you can do it in some
non-contrived way, then go for it.

Clearing the request buffer, checking for termination using strnlen, and
then using memcpy might not be too bad.

But after all, it is a false positive, so leaving things as they stand
is fine too.

Thanks,
Johan