[PATCH v4 23/38] drm: Detect overflow in drm_mm_reserve_node()

[Chris Wilson]

Protect ourselves from a caller passing in node.start + node.size that
will overflow and trick us into reserving that node.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
---
 drivers/gpu/drm/drm_mm.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
index 767cfd05c628..370cb8ee91c9 100644
--- a/drivers/gpu/drm/drm_mm.c
+++ b/drivers/gpu/drm/drm_mm.c
@@ -308,10 +308,9 @@ int drm_mm_reserve_node(struct drm_mm *mm, struct 
drm_mm_node *node)
        u64 hole_start, hole_end;
        u64 adj_start, adj_end;

-       if (WARN_ON(node->size == 0))
-               return -EINVAL;
-
        end = node->start + node->size;
+       if (unlikely(end <= node->start))
+               return -ENOSPC;

        /* Find the relevant hole to add our node to */
        hole = drm_mm_interval_tree_iter_first(&mm->interval_tree,
-- 
2.11.0