[PATCH v3 8/9] drm/rockchip: gem: Don't alloc/free gem buf when dev_private is invalid

[jeffy.chen@rock-chips.com (Jeffy Chen)]

After unbinding drm, the userspace may still has a chance to access
gem buf.

Add a sanity check for a NULL dev_private to prevent that from
happening.

Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
---

Changes in v3:
Address Daniel Vetter <daniel@ffwll.ch>'s comments.
Update commit message.

Changes in v2: None

 drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
index df9e570..205a3dc 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
@@ -184,6 +184,9 @@ static int rockchip_gem_alloc_buf(struct rockchip_gem_object *rk_obj,
 	struct drm_device *drm = obj->dev;
 	struct rockchip_drm_private *private = drm->dev_private;
 
+	if (!private)
+		return -ENODEV;
+
 	if (private->domain)
 		return rockchip_gem_alloc_iommu(rk_obj, alloc_kmap);
 	else
@@ -208,6 +211,11 @@ static void rockchip_gem_free_dma(struct rockchip_gem_object *rk_obj)
 
 static void rockchip_gem_free_buf(struct rockchip_gem_object *rk_obj)
 {
+	struct drm_device *drm = rk_obj->base.dev;
+
+	if (!drm->dev_private)
+		return;
+
 	if (rk_obj->pages)
 		rockchip_gem_free_iommu(rk_obj);
 	else
-- 
2.1.4