Re: [PATCH] staging: media: atomisp: Use kvfree_sensitive in a few places

[Alex Dewar]

On 2020-09-09 21:06, Dan Carpenter wrote:
> On Wed, Sep 09, 2020 at 08:53:50PM +0100, Alex Dewar wrote:
> > In the file pci/sh_css_params.c, there are a number of places where
> > memset+kvfree is used, where kvfree_sensitive could be used instead. Fix
> > these occurrences.
> This doesn't say *why* the commit is doing it.  There are two reasons:
> The worry with these is that the compiler could optimize away the memset
> because it sees the kfree().  Second using kvfree_sensitive() is more
> clear and readable.
Good point :)
> > Issue identified with Coccinelle.
> >
> > Signed-off-by: Alex Dewar <alex.dewar90@xxxxxxxxx>
> > ---
> >   .../staging/media/atomisp/pci/sh_css_params.c | 19 +++++++------------
> >   1 file changed, 7 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/staging/media/atomisp/pci/sh_css_params.c b/drivers/staging/media/atomisp/pci/sh_css_params.c
> > index 2c67c23b3700..d1b5d6608d52 100644
> > --- a/drivers/staging/media/atomisp/pci/sh_css_params.c
> > +++ b/drivers/staging/media/atomisp/pci/sh_css_params.c
> > @@ -4378,8 +4378,7 @@ ia_css_3a_statistics_free(struct ia_css_3a_statistics *me)
> >   	if (me) {
> >   		kvfree(me->rgby_data);
> >   		kvfree(me->data);
> > -		memset(me, 0, sizeof(struct ia_css_3a_statistics));
> > -		kvfree(me);
> > +		kvfree_sensitive(me, sizeof(struct ia_css_3a_statistics));
> I don't think ia_css_3a_statistics are sensitive at all.  What we're
> trying to protect are things like passwords.  Just delete the memset.
>
> Looking below, I don't think any of these are sensitive so just delete
> all the memsets.
This makes sense. I'll send a new patch. Thanks for the feedback!

Alex
> regards,
> dan carpenter