drm/vmwgfx: Stop accessing buffer objects which failed init

ttm_bo_init_reserved on failure puts the buffer object back which
causes it to be deleted, but kfree was still being called on the same
buffer in vmw_bo_create leading to a double free.

After the double free the vmw_gem_object_create_with_handle was
setting the gem function objects before checking the return status
of vmw_bo_create leading to null pointer access.

Fix the entire path by relaying on ttm_bo_init_reserved to delete the
buffer objects on failure and making sure the return status is checked
before setting the gem function objects on the buffer object.

Signed-off-by: Zack Rusin <[email protected]>
Fixes: 8afa13a0583f ("drm/vmwgfx: Implement DRIVER_GEM")
Reviewed-by: Maaz Mombasawala <[email protected]>
Reviewed-by: Martin Krastev <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c b/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c
index f042e22b8b59..51bd1f8c5cc4 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_gem.c
@@ -127,11 +127,11 @@ int vmw_gem_object_create_with_handle(struct vmw_private *dev_priv,
 	};
 
 	ret = vmw_bo_create(dev_priv, &params, p_vbo);
-
-	(*p_vbo)->tbo.base.funcs = &vmw_gem_object_funcs;
 	if (ret != 0)
 		goto out_no_bo;
 
+	(*p_vbo)->tbo.base.funcs = &vmw_gem_object_funcs;
+
 	ret = drm_gem_handle_create(filp, &(*p_vbo)->tbo.base, handle);
 	/* drop reference from allocate - handle holds it now */
 	drm_gem_object_put(&(*p_vbo)->tbo.base);