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,URIBL_BLOCKED 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 858FAC282DA for ; Sun, 3 Feb 2019 13:52:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 58088218F0 for ; Sun, 3 Feb 2019 13:52:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728623AbfBCNuW (ORCPT ); Sun, 3 Feb 2019 08:50:22 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:53300 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728138AbfBCNtu (ORCPT ); Sun, 3 Feb 2019 08:49:50 -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 1gqI9b-0003wG-S4; Sun, 03 Feb 2019 13:49:48 +0000 Received: from ben by deadeye with local (Exim 4.92-RC4) (envelope-from ) id 1gqI9Z-000705-8T; Sun, 03 Feb 2019 14:49:45 +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 , "Jiri Kosina" , "Breno Leitao" Date: Sun, 03 Feb 2019 14:45:08 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 117/305] HID: hiddev: fix potential Spectre v1 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: Breno Leitao commit f11274396a538b31bc010f782e05c2ce3f804c13 upstream. uref->usage_index can be indirectly controlled by userspace, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This field is used as an array index by the hiddev_ioctl_usage() function, when 'cmd' is either HIDIOCGCOLLECTIONINDEX, HIDIOCGUSAGES or HIDIOCSUSAGES. For cmd == HIDIOCGCOLLECTIONINDEX case, uref->usage_index is compared to field->maxusage and then used as an index to dereference field->usage array. The same thing happens to the cmd == HIDIOC{G,S}USAGES cases, where uref->usage_index is checked against an array maximum value and then it is used as an index in an array. This is a summary of the HIDIOCGCOLLECTIONINDEX case, which matches the traditional Spectre V1 first load: copy_from_user(uref, user_arg, sizeof(*uref)) if (uref->usage_index >= field->maxusage) goto inval; i = field->usage[uref->usage_index].collection_index; return i; This patch fixes this by sanitizing field uref->usage_index before using it to index field->usage (HIDIOCGCOLLECTIONINDEX) or field->value in HIDIOC{G,S}USAGES arrays, thus, avoiding speculation in the first load. Signed-off-by: Breno Leitao -- v2: Contemplate cmd == HIDIOC{G,S}USAGES case Signed-off-by: Jiri Kosina Signed-off-by: Ben Hutchings --- drivers/hid/usbhid/hiddev.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) --- a/drivers/hid/usbhid/hiddev.c +++ b/drivers/hid/usbhid/hiddev.c @@ -521,14 +521,24 @@ static noinline int hiddev_ioctl_usage(s if (cmd == HIDIOCGCOLLECTIONINDEX) { if (uref->usage_index >= field->maxusage) goto inval; + uref->usage_index = + array_index_nospec(uref->usage_index, + field->maxusage); } else if (uref->usage_index >= field->report_count) goto inval; } - if ((cmd == HIDIOCGUSAGES || cmd == HIDIOCSUSAGES) && - (uref_multi->num_values > HID_MAX_MULTI_USAGES || - uref->usage_index + uref_multi->num_values > field->report_count)) - goto inval; + if (cmd == HIDIOCGUSAGES || cmd == HIDIOCSUSAGES) { + if (uref_multi->num_values > HID_MAX_MULTI_USAGES || + uref->usage_index + uref_multi->num_values > + field->report_count) + goto inval; + + uref->usage_index = + array_index_nospec(uref->usage_index, + field->report_count - + uref_multi->num_values); + } switch (cmd) { case HIDIOCGUSAGE: