RE: [PATCH] drivers/soc: Remove all strcpy() uses in favor of strscpy()

From: David Laight <David.Laight@ACULAB.COM>
To: 'Geert Uytterhoeven' <geert@linux-m68k.org>,
	Len Baker <len.baker@gmx.com>
Cc: Kees Cook <keescook@chromium.org>, Andy Gross <agross@kernel.org>,
	"Bjorn Andersson" <bjorn.andersson@linaro.org>,
	Magnus Damm <magnus.damm@gmail.com>,
	Santosh Shilimkar <ssantosh@kernel.org>,
	"linux-hardening@vger.kernel.org"
	<linux-hardening@vger.kernel.org>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: RE: [PATCH] drivers/soc: Remove all strcpy() uses in favor of strscpy()
Date: Wed, 28 Jul 2021 08:36:44 +0000	[thread overview]
Message-ID: <80f4574c9f6c4c6780735b0fffd83363@AcuMS.aculab.com> (raw)
In-Reply-To: <CAMuHMdUdmv+YmdtjGJV2Lp_Rvar4kN4uSgSTYqXX9CtCJ+qoRw@mail.gmail.com>

From: Geert Uytterhoeven
> Sent: 26 July 2021 09:03
> 
> Hi Len,
> 
> On Sun, Jul 25, 2021 at 5:15 PM Len Baker <len.baker@gmx.com> wrote:
> > strcpy() performs no bounds checking on the destination buffer. This
> > could result in linear overflows beyond the end of the buffer, leading
> > to all kinds of misbehaviors. The safe replacement is strscpy().
> >
> > Signed-off-by: Len Baker <len.baker@gmx.com>
> 
> Thanks for your patch!
> 
> > ---
> > This is a task of the KSPP [1]
> >
> > [1] https://github.com/KSPP/linux/issues/88
> 
> Any chance the almost one year old question in that ticket can be
> answered?
> 
> >  drivers/soc/renesas/rcar-sysc.c     |  6 ++++--
> 
> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
> 
> But please see my comments below...
> 
> > --- a/drivers/soc/renesas/r8a779a0-sysc.c
> > +++ b/drivers/soc/renesas/r8a779a0-sysc.c
> > @@ -404,19 +404,21 @@ static int __init r8a779a0_sysc_pd_init(void)
> >         for (i = 0; i < info->num_areas; i++) {
> >                 const struct r8a779a0_sysc_area *area = &info->areas[i];
> >                 struct r8a779a0_sysc_pd *pd;
> > +               size_t area_name_size;
> 
> I wouldn't mind a shorter name, like "n".
> 
> >
> >                 if (!area->name) {
> >                         /* Skip NULLified area */
> >                         continue;
> >                 }
> >
> > -               pd = kzalloc(sizeof(*pd) + strlen(area->name) + 1, GFP_KERNEL);
> > +               area_name_size = strlen(area->name) + 1;
> > +               pd = kzalloc(sizeof(*pd) + area_name_size, GFP_KERNEL);
> >                 if (!pd) {
> >                         error = -ENOMEM;
> >                         goto out_put;
> >                 }
> >
> > -               strcpy(pd->name, area->name);
> > +               strscpy(pd->name, area->name, area_name_size);

You can just use memcpy().

	David

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