drm/vc4: Fix OOPSes from trying to cache a partially constructed BO.

commit ca39b449f6d03e8235969f12f5dd25b8eb4304d6 upstream.

If a CMA allocation failed, the partially constructed BO would be
unreferenced through the normal path, and we might choose to put it in
the BO cache.  If we then reused it before it expired from the cache,
the kernel would OOPS.

Signed-off-by: Eric Anholt <eric@anholt.net>
Fixes: c826a6e10644 ("drm/vc4: Add a BO cache.")
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170301185602.6873-2-eric@anholt.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/vc4/vc4_bo.c b/drivers/gpu/drm/vc4/vc4_bo.c
index 55bbadc86a1ee45205360fb26e8525a8326db017..b20e9c8298763f81d27c8cbaecb4e642e7d62625 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_bo.c
+++ b/drivers/gpu/drm/vc4/vc4_bo.c
@@ -322,6 +322,14 @@ void vc4_free_object(struct drm_gem_object *gem_bo)
                goto out;
        }
 
+       /* If this object was partially constructed but CMA allocation
+        * had failed, just free it.
+        */
+       if (!bo->base.vaddr) {
+               vc4_bo_destroy(bo);
+               goto out;
+       }
+
        cache_list = vc4_get_cache_list_for_size(dev, gem_bo->size);
        if (!cache_list) {
                vc4_bo_destroy(bo);