[PATCH] drm: multiplication overflow in vmw_fence_obj_wait_ioctl()

[yongjianxuxuyongjia...@gmail.com]

From: Yongjian Xu <xuyongjia...@gmail.com>

arg->time_out_us comes from user-space, then overflow may occur in this line:
        uint64_t wait_timeout = ((uint64_t)arg->timeout_us * HZ);
This is not a serious problem, but still a bug.

Signed-off-by: Yongjian Xu <xuyongjiande at gmail.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_fence.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c 
b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
index c62d20e..f9b0f8b 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
@@ -689,6 +689,8 @@ int vmw_fence_obj_wait_ioctl(struct drm_device *dev, void 
*data,
        struct vmw_fence_obj *fence;
        struct ttm_object_file *tfile = vmw_fpriv(file_priv)->tfile;
        int ret;
+       if (arg->timeout_us > (0xffffffffffffffff / HZ))
+               return -EINVAL;
        uint64_t wait_timeout = ((uint64_t)arg->timeout_us * HZ);

        /*
-- 
1.7.9.5