drm/vmwgfx: avoid calling vzalloc with a 0 size in vmw_get_cap_3d_ioctl()

BugLink: http://bugs.launchpad.net/bugs/1682140
commit 63774069d9527a1aeaa4aa20e929ef5e8e9ecc38 upstream.

In vmw_get_cap_3d_ioctl(), a user can supply 0 for a size that is
used in vzalloc(). This eventually calls dump_stack() (in warn_alloc()),
which can leak useful addresses to dmesg.

Add check to avoid a size of 0.

Signed-off-by: Murray McAllister <murray.mcallister@insomniasec.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c
index b8c6a03c8c54df15def2d359ee5253f213f1816e..1802d0e7fab8f23fda6b954efb3a1426a3ad18f2 100644 (file)
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c
@@ -186,7 +186,7 @@ int vmw_get_cap_3d_ioctl(struct drm_device *dev, void *data,
        bool gb_objects = !!(dev_priv->capabilities & SVGA_CAP_GBOBJECTS);
        struct vmw_fpriv *vmw_fp = vmw_fpriv(file_priv);
 
-       if (unlikely(arg->pad64 != 0)) {
+       if (unlikely(arg->pad64 != 0 || arg->max_size == 0)) {
                DRM_ERROR("Illegal GET_3D_CAP argument.\n");
                return -EINVAL;
        }