drm/vmwgfx: NULL pointer dereference in vmw_surface_define_ioctl()

commit 36274ab8c596f1240c606bb514da329add2a1bcd upstream.

Before memory allocations vmw_surface_define_ioctl() checks the
upper-bounds of a user-supplied size, but does not check if the
supplied size is 0.

Add check to avoid NULL pointer dereferences.

Signed-off-by: Murray McAllister <murray.mcallister@insomniasec.com>
Reviewed-by: Sinclair Yeh <syeh@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 0795d17..912b083 100644 (file)
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
@@ -1307,8 +1307,8 @@ int vmw_surface_define_ioctl(struct drm_device *dev, void *data,
        for (i = 0; i < DRM_VMW_MAX_SURFACE_FACES; ++i)
                num_sizes += req->mip_levels[i];
 
-       if (num_sizes > DRM_VMW_MAX_SURFACE_FACES *
-           DRM_VMW_MAX_MIP_LEVELS)
+       if (num_sizes > DRM_VMW_MAX_SURFACE_FACES * DRM_VMW_MAX_MIP_LEVELS ||
+           num_sizes == 0)
                return -EINVAL;
 
        size = vmw_user_surface_size + 128 +