From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756564Ab1KWGMH (ORCPT ); Wed, 23 Nov 2011 01:12:07 -0500 Received: from mail-yw0-f46.google.com ([209.85.213.46]:35097 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751984Ab1KWGMF (ORCPT ); Wed, 23 Nov 2011 01:12:05 -0500 From: Xi Wang Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Subject: [PATCH] drm: integer overflow in drm_mode_dirtyfb_ioctl() Date: Wed, 23 Nov 2011 01:12:01 -0500 Message-Id: Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, security@kernel.org To: David Airlie Mime-Version: 1.0 (Apple Message framework v1084) X-Mailer: Apple Mail (2.1084) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There is a potential integer overflow in drm_mode_dirtyfb_ioctl() if userspace passes in a large num_clips. The call to kmalloc would allocate a small buffer, and the call to fb->funcs->dirty may result in a memory corruption. Reported-by: Haogang Chen Signed-off-by: Xi Wang --- drivers/gpu/drm/drm_crtc.c | 4 ++++ include/drm/drm_mode.h | 2 ++ 2 files changed, 6 insertions(+), 0 deletions(-) diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index 405c63b..8323fc3 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -1873,6 +1873,10 @@ int drm_mode_dirtyfb_ioctl(struct drm_device *dev, } if (num_clips && clips_ptr) { + if (num_clips < 0 || num_clips > DRM_MODE_FB_DIRTY_MAX_CLIPS) { + ret = -EINVAL; + goto out_err1; + } clips = kzalloc(num_clips * sizeof(*clips), GFP_KERNEL); if (!clips) { ret = -ENOMEM; diff --git a/include/drm/drm_mode.h b/include/drm/drm_mode.h index d30bedf..ddd46db 100644 --- a/include/drm/drm_mode.h +++ b/include/drm/drm_mode.h @@ -235,6 +235,8 @@ struct drm_mode_fb_cmd { #define DRM_MODE_FB_DIRTY_ANNOTATE_FILL 0x02 #define DRM_MODE_FB_DIRTY_FLAGS 0x03 +#define DRM_MODE_FB_DIRTY_MAX_CLIPS 256 + /* * Mark a region of a framebuffer as dirty. * -- 1.7.5.4