From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Herrmann Subject: [PATCH v2 5/6] drm/crtc: add sanity checks to create_dumb() Date: Thu, 23 Jan 2014 13:53:15 +0100 Message-ID: <1390481595-512-1-git-send-email-dh.herrmann@gmail.com> References: <1390245989-13280-6-git-send-email-dh.herrmann@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-we0-f172.google.com (mail-we0-f172.google.com [74.125.82.172]) by gabe.freedesktop.org (Postfix) with ESMTP id AC492FBEC4 for ; Thu, 23 Jan 2014 04:53:25 -0800 (PST) Received: by mail-we0-f172.google.com with SMTP id q58so1108655wes.17 for ; Thu, 23 Jan 2014 04:53:23 -0800 (PST) In-Reply-To: <1390245989-13280-6-git-send-email-dh.herrmann@gmail.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dri-devel-bounces@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org To: dri-devel@lists.freedesktop.org Cc: Daniel Vetter List-Id: dri-devel@lists.freedesktop.org Lets make sure some basic expressions are always true: bpp != NULL width != NULL height != NULL stride = bpp * width < 2^32 size = stride * height < 2^32 PAGE_ALIGN(size) < 2^32 At least the udl driver doesn't check for multiplication-overflows, so lets just make sure it will never happen. These checks allow drivers to do any 32bit math without having to test for mult-overflows themselves. The two divisions might hurt performance a bit, but dumb_create() is only used for scanout-buffers, so that should be fine. We could use 64bit math to avoid the divisions, but that may be slow on 32bit machines.. Or maybe there should just be a "safe_mult32()" helper, which currently doesn't exist (I think?). Reviewed-by: Daniel Vetter Signed-off-by: David Herrmann --- drivers/gpu/drm/drm_crtc.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index 266a01d..2b50702 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -3738,9 +3738,26 @@ int drm_mode_create_dumb_ioctl(struct drm_device *dev, void *data, struct drm_file *file_priv) { struct drm_mode_create_dumb *args = data; + u32 cpp, stride, size; if (!dev->driver->dumb_create) return -ENOSYS; + if (!args->width || !args->height || !args->bpp) + return -EINVAL; + + /* overflow checks for 32bit size calculations */ + cpp = DIV_ROUND_UP(args->bpp, 8); + if (cpp > 0xffffffffU / args->width) + return -EINVAL; + stride = cpp * args->width; + if (args->height > 0xffffffffU / stride) + return -EINVAL; + + /* test for wrap-around */ + size = args->height * stride; + if (PAGE_ALIGN(size) == 0) + return -EINVAL; + return dev->driver->dumb_create(file_priv, dev, args); } -- 1.8.5.3