drm/vmwgfx: fix integer overflow in vmw_surface_define_ioctl()

commit e7e11f99564222d82f0ce84bd521e57d78a6b678 upstream.

In vmw_surface_define_ioctl(), the 'num_sizes' is the sum of the
'req->mip_levels' array. This array can be assigned any value from
the user space. As both the 'num_sizes' and the array is uint32_t,
it is easy to make 'num_sizes' overflow. The later 'mip_levels' is
used as the loop count. This can lead an oob write. Add the check of
'req->mip_levels' to avoid this.

Signed-off-by: Li Qiang <liqiang6-s@360.cn>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
index 912b083..e7af6c8 100644 (file)
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
@@ -1304,8 +1304,11 @@ int vmw_surface_define_ioctl(struct drm_device *dev, void *data,
                        128;
 
        num_sizes = 0;
-       for (i = 0; i < DRM_VMW_MAX_SURFACE_FACES; ++i)
+       for (i = 0; i < DRM_VMW_MAX_SURFACE_FACES; ++i) {
+               if (req->mip_levels[i] > DRM_VMW_MAX_MIP_LEVELS)
+                       return -EINVAL;
                num_sizes += req->mip_levels[i];
+       }
 
        if (num_sizes > DRM_VMW_MAX_SURFACE_FACES * DRM_VMW_MAX_MIP_LEVELS ||
            num_sizes == 0)