Re: [Intel-gfx] [PATCH] drm/i915/ttm: ensure we release the intel_memory_region

[Matthew Auld <matthew.william.auld@gmail.com>]

On Thu, 19 Aug 2021 at 08:25, Thomas Hellström
<thomas.hellstrom@linux.intel.com> wrote:
>
> On Wed, 2021-08-18 at 18:12 +0100, Matthew Auld wrote:
> > If the ttm_bo_init_reserved() call fails ensure we also release the
> > region, otherwise we leak the reference, or worse hit some uaf, when
> > we
> > start using the objects.list. Also remove the make_unshrinkable call
> > here, which doesn't do anything.
> >
> > Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> > Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 7 +++++--
> >  1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> > b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> > index 771eb2963123..2e8cdcd5e4f7 100644
> > --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> > +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> > @@ -909,7 +909,6 @@ int __i915_gem_ttm_object_init(struct
> > intel_memory_region *mem,
> >         drm_gem_private_object_init(&i915->drm, &obj->base, size);
> >         i915_gem_object_init(obj, &i915_gem_ttm_obj_ops, &lock_class,
> > flags);
> >         i915_gem_object_init_memory_region(obj, mem);
> > -       i915_gem_object_make_unshrinkable(obj);
> >         INIT_RADIX_TREE(&obj->ttm.get_io_page.radix, GFP_KERNEL |
> > __GFP_NOWARN);
> >         mutex_init(&obj->ttm.get_io_page.lock);
> >         bo_type = (obj->flags & I915_BO_ALLOC_USER) ?
> > ttm_bo_type_device :
> > @@ -932,7 +931,7 @@ int __i915_gem_ttm_object_init(struct
> > intel_memory_region *mem,
> >                                    page_size >> PAGE_SHIFT,
> >                                    &ctx, NULL, NULL,
> > i915_ttm_bo_destroy);
> >         if (ret)
> > -               return i915_ttm_err_to_gem(ret);
> > +               goto err_release_mr;
>
> IIRC when ttm_object_init_reserved fails, it will call ttm_bo_put()
> which will eventually end up in i915_ttm_bo_destroy() which will do the
> right thing?

Ah right, missed that.

>
> /Thomas
>
>