drm: prevent a harmless integer overflow in drm_legacy_sg_alloc()

There is an integer overflow when we round up to PAGE_SIZE, but it's
harmless because we never re-use "request->size" for anything meaningful.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200228092321.axulddmkxrujkmas@kili.mountain

diff --git a/drivers/gpu/drm/drm_scatter.c b/drivers/gpu/drm/drm_scatter.c
index d5c386154246e3da2ee3911862b1de4d5ee95195..ca520028b2cb1db39d10d6de223524299737d064 100644 (file)
--- a/drivers/gpu/drm/drm_scatter.c
+++ b/drivers/gpu/drm/drm_scatter.c
@@ -99,6 +99,9 @@ int drm_legacy_sg_alloc(struct drm_device *dev, void *data,
        if (!drm_core_check_feature(dev, DRIVER_SG))
                return -EOPNOTSUPP;
 
+       if (request->size > SIZE_MAX - PAGE_SIZE)
+               return -EINVAL;
+
        if (dev->sg)
                return -EINVAL;