linux-kernel - Re: [PATCH] drm/mm: avoid possible null pointer dereference

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Date:	Mon, 23 May 2016 14:56:45 +0200
From:	Daniel Vetter <daniel@...ll.ch>
To:	Eric Engestrom <eric.engestrom@...tec.com>
Cc:	Heinrich Schuchardt <xypron.glpk@....de>,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] drm/mm: avoid possible null pointer dereference

On Mon, May 23, 2016 at 11:27:14AM +0100, Eric Engestrom wrote:
> On Wed, May 18, 2016 at 10:17:19PM +0200, Heinrich Schuchardt wrote:
> > Do not dereference node before the check if node is NULL.
> > 
> > Signed-off-by: Heinrich Schuchardt <xypron.glpk@....de>
> > ---
> >  drivers/gpu/drm/drm_mm.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
> > index 04de6fd..cb39f45 100644
> > --- a/drivers/gpu/drm/drm_mm.c
> > +++ b/drivers/gpu/drm/drm_mm.c
> > @@ -179,12 +179,14 @@ static void drm_mm_insert_helper(struct drm_mm_node *hole_node,
> >  int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node)
> >  {
> >  	struct drm_mm_node *hole;
> > -	u64 end = node->start + node->size;
> > +	u64 end;
> >  	u64 hole_start;
> >  	u64 hole_end;
> >  
> >  	BUG_ON(node == NULL);
> >  
> > +	end = node->start + node->size;
> > +
> >  	/* Find the relevant hole to add our node to */
> >  	drm_mm_for_each_hole(hole, mm, hole_start, hole_end) {
> >  		if (hole_start > node->start || hole_end < end)
> > -- 
> > 2.1.4
> 
> Reviewed-by: Eric Engestrom <eric.engestrom@...tec.com>

Applied to drm-misc, thanks.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch