KASAN: use-after-free Read in vgem_gem_dumb_create
Dan Carpenter
dan.carpenter at oracle.com
Sat Feb 1 16:25:37 UTC 2020
On Sat, Feb 01, 2020 at 05:02:47PM +0800, Hillf Danton wrote:
>
> On Sat, 1 Feb 2020 09:17:57 +0300 Dan Carpenter wrote:
> > On Sat, Feb 01, 2020 at 12:32:09PM +0800, Hillf Danton wrote:
> > >
> > > Release obj in error path.
> > >
> > > --- a/drivers/gpu/drm/vgem/vgem_drv.c
> > > +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> > > @@ -196,10 +196,10 @@ static struct drm_gem_object *vgem_gem_c
> > > return ERR_CAST(obj);
> > >
> > > ret = drm_gem_handle_create(file, &obj->base, handle);
> > > - drm_gem_object_put_unlocked(&obj->base);
> > > - if (ret)
> > > + if (ret) {
> > > + drm_gem_object_put_unlocked(&obj->base);
> > > return ERR_PTR(ret);
> > > -
> > > + }
> > > return &obj->base;
> >
> > Oh yeah. It's weird that we never noticed the success path was broken.
> > It's been that way for three years and no one noticed at all. Very
> > strange.
> >
> > Anyway, it already gets freed on error in drm_gem_handle_create() so
> > we should just delete the drm_gem_object_put_unlocked() here it looks
> > like.
>
> Good catch, Dan :P
> Would you please post a patch sometime convenient next week?
Sure. Will do.
regards,
dan carpenter
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