From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-Id: <20111207161215.272114271@clark.kroah.org> Date: Wed, 07 Dec 2011 08:11:08 -0800 From: Greg KH To: , Cc: , , , Xi Wang , Dave Airlie Subject: [006/104] drm: integer overflow in drm_mode_dirtyfb_ioctl() In-Reply-To: <20111207161246.GA10995@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xi Wang commit a5cd335165e31db9dbab636fd29895d41da55dd2 upstream. 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 Signed-off-by: Dave Airlie Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_crtc.c | 4 ++++ include/drm/drm_mode.h | 2 ++ 2 files changed, 6 insertions(+) --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -1868,6 +1868,10 @@ int drm_mode_dirtyfb_ioctl(struct drm_de } 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; --- a/include/drm/drm_mode.h +++ b/include/drm/drm_mode.h @@ -233,6 +233,8 @@ 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. *