drm/ttm: fix ttm_bo_add_ttm(user) failure path

ttm_tt_destroy kfrees passed object, so we need to nullify
a reference to it.

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: stable@kernel.org
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 56619f64b6bf..384116afe5b7 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -353,8 +353,10 @@ static int ttm_bo_add_ttm(struct ttm_buffer_object *bo, bool zero_alloc)
 
                 ret = ttm_tt_set_user(bo->ttm, current,
                                       bo->buffer_start, bo->num_pages);
-                if (unlikely(ret != 0))
+                if (unlikely(ret != 0)) {
                         ttm_tt_destroy(bo->ttm);
+                        bo->ttm = NULL;
+                }
                 break;
         default:
                 printk(KERN_ERR TTM_PFX "Illegal buffer object type\n");