On Wed 08 May 19:03 PDT 2019, Brian Masney wrote:
> The msm_gem_object structure contains resv and _resv fields that are
> no longer needed since the reservation object is now stored on
> drm_gem_object. msm_atomic_prepare_fb() and msm_atomic_prepare_fb()
> both referenced the wrong reservation object, and would lead to an
> attempt to dereference a NULL pointer. Correct those two cases to
> point to the correct reservation object.
>
> Signed-off-by: Brian Masney <masn...@onstation.org>
> Fixes: dd55cf6929e6 ("drm: msm: Switch to use drm_gem_object
> reservation_object")
Reviewed-by: Bjorn Andersson <bjorn.anders...@linaro.org>
Tested-by: Bjorn Andersson <bjorn.anders...@linaro.org>
This resolves a NULL-pointer dereference about to show up in v5.2-rc1,
so please pick this up for -rc.
Regards,
Bjorn
> ---
> Patch introduced in v2
>
> drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c | 4 +---
> drivers/gpu/drm/msm/msm_atomic.c | 4 +---
> drivers/gpu/drm/msm/msm_gem.c | 3 ---
> drivers/gpu/drm/msm/msm_gem.h | 4 ----
> 4 files changed, 2 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> index da1f727d7495..ce1a555e1f31 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> @@ -780,7 +780,6 @@ static int dpu_plane_prepare_fb(struct drm_plane *plane,
> struct dpu_plane_state *pstate = to_dpu_plane_state(new_state);
> struct dpu_hw_fmt_layout layout;
> struct drm_gem_object *obj;
> - struct msm_gem_object *msm_obj;
> struct dma_fence *fence;
> struct dpu_kms *kms = _dpu_plane_get_kms(&pdpu->base);
> int ret;
> @@ -799,8 +798,7 @@ static int dpu_plane_prepare_fb(struct drm_plane *plane,
> * implicit fence and fb prepare by hand here.
> */
> obj = msm_framebuffer_bo(new_state->fb, 0);
> - msm_obj = to_msm_bo(obj);
> - fence = reservation_object_get_excl_rcu(msm_obj->resv);
> + fence = reservation_object_get_excl_rcu(obj->resv);
> if (fence)
> drm_atomic_set_fence_for_plane(new_state, fence);
>
> diff --git a/drivers/gpu/drm/msm/msm_atomic.c
> b/drivers/gpu/drm/msm/msm_atomic.c
> index f5b1256e32b6..131c23a267ee 100644
> --- a/drivers/gpu/drm/msm/msm_atomic.c
> +++ b/drivers/gpu/drm/msm/msm_atomic.c
> @@ -49,15 +49,13 @@ int msm_atomic_prepare_fb(struct drm_plane *plane,
> struct msm_drm_private *priv = plane->dev->dev_private;
> struct msm_kms *kms = priv->kms;
> struct drm_gem_object *obj;
> - struct msm_gem_object *msm_obj;
> struct dma_fence *fence;
>
> if (!new_state->fb)
> return 0;
>
> obj = msm_framebuffer_bo(new_state->fb, 0);
> - msm_obj = to_msm_bo(obj);
> - fence = reservation_object_get_excl_rcu(msm_obj->resv);
> + fence = reservation_object_get_excl_rcu(obj->resv);
>
> drm_atomic_set_fence_for_plane(new_state, fence);
>
> diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
> index 31d5a744d84f..947508e8269d 100644
> --- a/drivers/gpu/drm/msm/msm_gem.c
> +++ b/drivers/gpu/drm/msm/msm_gem.c
> @@ -973,9 +973,6 @@ static int msm_gem_new_impl(struct drm_device *dev,
> msm_obj->flags = flags;
> msm_obj->madv = MSM_MADV_WILLNEED;
>
> - if (resv)
> - msm_obj->base.resv = resv;
> -
> INIT_LIST_HEAD(&msm_obj->submit_entry);
> INIT_LIST_HEAD(&msm_obj->vmas);
>
> diff --git a/drivers/gpu/drm/msm/msm_gem.h b/drivers/gpu/drm/msm/msm_gem.h
> index c5ac781dffee..812d1b1369a5 100644
> --- a/drivers/gpu/drm/msm/msm_gem.h
> +++ b/drivers/gpu/drm/msm/msm_gem.h
> @@ -86,10 +86,6 @@ struct msm_gem_object {
>
> struct llist_node freed;
>
> - /* normally (resv == &_resv) except for imported bo's */
> - struct reservation_object *resv;
> - struct reservation_object _resv;
> -
> /* For physically contiguous buffers. Used when we don't have
> * an IOMMU. Also used for stolen/splashscreen buffer.
> */
> --
> 2.20.1
>
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