Re: [PATCH v4 2/3] drivers/soc/renesas: Prefer memcpy over strcpy

[Christophe JAILLET]

Hi,

Le 08/08/2021 à 17:35, Bernd Petrovitsch a écrit :
> Hi all!
>
> On 08/08/2021 14:50, Len Baker 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. So, use memcpy() as a safe replacement.
> >
> > This is a previous step in the path to remove the strcpy() function
> > entirely from the kernel.
> >
> > Signed-off-by: Len Baker <len.baker@xxxxxxx>
> > ---
> >   drivers/soc/renesas/r8a779a0-sysc.c | 6 ++++--
> >   drivers/soc/renesas/rcar-sysc.c     | 6 ++++--
> >   2 files changed, 8 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/soc/renesas/r8a779a0-sysc.c b/drivers/soc/renesas/r8a779a0-sysc.c
> > index d464ffa1be33..7410b9fa9846 100644
> > --- 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 n;
> >
> >   		if (!area->name) {
> >   			/* Skip NULLified area */
> >   			continue;
> >   		}
> >
> > -		pd = kzalloc(sizeof(*pd) + strlen(area->name) + 1, GFP_KERNEL);
> > +		n = strlen(area->name) + 1;
> > +		pd = kzalloc(sizeof(*pd) + n, GFP_KERNEL);
> Zeroing the allocated bytes is not needed since it's completly
> overwritten with the strcpy()/memcpy().

The strcpy()/memcpy() only overwrites the pd->name field, not the whole 
pd structure.
I think that it is needed to keep the kzalloc.

Just my 2c,
CJ

> >   		if (!pd) {
> >   			error = -ENOMEM;
> >   			goto out_put;
> >   		}
> >
> > -		strcpy(pd->name, area->name);
> > +		memcpy(pd->name, area->name, n);
> >   		pd->genpd.name = pd->name;
> >   		pd->pdr = area->pdr;
> >   		pd->flags = area->flags;
>
> And similar for the second hunk.
>
> MfG,
> 	Bernd