From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E694FC169C4 for ; Sun, 3 Feb 2019 13:55:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BF0AB218D8 for ; Sun, 3 Feb 2019 13:55:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728584AbfBCNza (ORCPT ); Sun, 3 Feb 2019 08:55:30 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:54542 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729097AbfBCNyq (ORCPT ); Sun, 3 Feb 2019 08:54:46 -0500 Received: from cable-78.29.236.164.coditel.net ([78.29.236.164] helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gqIEO-0003te-KQ; Sun, 03 Feb 2019 13:54:44 +0000 Received: from ben by deadeye with local (Exim 4.92-RC4) (envelope-from ) id 1gqIDX-000086-1c; Sun, 03 Feb 2019 14:53:51 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Gustavo A. R. Silva" , "Daniel Vetter" Date: Sun, 03 Feb 2019 14:45:08 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 302/305] drm/ioctl: Fix Spectre v1 vulnerabilities In-Reply-To: X-SA-Exim-Connect-IP: 78.29.236.164 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.63-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: "Gustavo A. R. Silva" commit 505b5240329b922f21f91d5b5d1e535c805eca6d upstream. nr is indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: drivers/gpu/drm/drm_ioctl.c:805 drm_ioctl() warn: potential spectre issue 'dev->driver->ioctls' [r] drivers/gpu/drm/drm_ioctl.c:810 drm_ioctl() warn: potential spectre issue 'drm_ioctls' [r] (local cap) drivers/gpu/drm/drm_ioctl.c:892 drm_ioctl_flags() warn: potential spectre issue 'drm_ioctls' [r] (local cap) Fix this by sanitizing nr before using it to index dev->driver->ioctls and drm_ioctls. Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 Signed-off-by: Gustavo A. R. Silva Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20181220000015.GA18973@embeddedor [bwh: Backported to 3.16: adjust filename, context] Signed-off-by: Ben Hutchings --- drivers/gpu/drm/drm_drv.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -49,6 +49,7 @@ #include #include #include +#include #include #include @@ -360,7 +361,10 @@ long drm_ioctl(struct file *filp, if ((nr >= DRM_COMMAND_BASE) && (nr < DRM_COMMAND_END) && (nr < DRM_COMMAND_BASE + dev->driver->num_ioctls)) { u32 drv_size; - ioctl = &dev->driver->ioctls[nr - DRM_COMMAND_BASE]; + unsigned int index = nr - DRM_COMMAND_BASE; + + index = array_index_nospec(index, dev->driver->num_ioctls); + ioctl = &dev->driver->ioctls[index]; drv_size = _IOC_SIZE(ioctl->cmd_drv); usize = asize = _IOC_SIZE(cmd); if (drv_size > asize) @@ -370,6 +374,7 @@ long drm_ioctl(struct file *filp, else if ((nr >= DRM_COMMAND_END) || (nr < DRM_COMMAND_BASE)) { u32 drv_size; + nr = array_index_nospec(nr, DRM_CORE_IOCTL_COUNT); ioctl = &drm_ioctls[nr]; drv_size = _IOC_SIZE(ioctl->cmd); @@ -465,6 +470,7 @@ bool drm_ioctl_flags(unsigned int nr, un if (nr >= DRM_CORE_IOCTL_COUNT) return false; + nr = array_index_nospec(nr, DRM_CORE_IOCTL_COUNT); *flags = drm_ioctls[nr].flags; return true;