linux-hardening - Re: [PATCH][next] nouveau/svm: Use kvcalloc() instead of kvzalloc()

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Message-ID: <202110211002.CB975695@keescook>
Date:   Thu, 21 Oct 2021 10:03:19 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Karol Herbst <kherbst@...hat.com>
Cc:     "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Ben Skeggs <bskeggs@...hat.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        nouveau <nouveau@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-hardening@...r.kernel.org
Subject: Re: [PATCH][next] nouveau/svm: Use kvcalloc() instead of kvzalloc()

On Wed, Sep 29, 2021 at 05:28:47AM +0200, Karol Herbst wrote:
> Lack of documentation inside Linux here is a bit annoying, but do I
> understand it correctly, that the main (and probably only) difference
> is that kvcalloc checks whether the multiplication overflows and
> returns NULL in this case?

That's correct. :)

> On Wed, Sep 29, 2021 at 12:21 AM Gustavo A. R. Silva
> <gustavoars@...nel.org> wrote:
> >
> > Use 2-factor argument form kvcalloc() instead of kvzalloc().
> >
> > Link: https://github.com/KSPP/linux/issues/162
> > Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>

Reviewed-by: Kees Cook <keescook@...omium.org>

> > ---
> >  drivers/gpu/drm/nouveau/nouveau_svm.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
> > index b0c3422cb01f..1a896a24288a 100644
> > --- a/drivers/gpu/drm/nouveau/nouveau_svm.c
> > +++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
> > @@ -992,7 +992,7 @@ nouveau_svm_fault_buffer_ctor(struct nouveau_svm *svm, s32 oclass, int id)
> >         if (ret)
> >                 return ret;
> >
> > -       buffer->fault = kvzalloc(sizeof(*buffer->fault) * buffer->entries, GFP_KERNEL);
> > +       buffer->fault = kvcalloc(sizeof(*buffer->fault), buffer->entries, GFP_KERNEL);
> >         if (!buffer->fault)
> >                 return -ENOMEM;
> >
> > --
> > 2.27.0
> >
> 

-- 
Kees Cook