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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2C0A8C433EF for ; Mon, 14 Feb 2022 09:30:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241526AbiBNJab (ORCPT ); Mon, 14 Feb 2022 04:30:31 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:43072 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243344AbiBNJaQ (ORCPT ); Mon, 14 Feb 2022 04:30:16 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 86657AE45; Mon, 14 Feb 2022 01:29:29 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 2E34FB80DC7; Mon, 14 Feb 2022 09:29:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 36E86C340E9; Mon, 14 Feb 2022 09:29:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1644830966; bh=cUNXPxURKpD8NzufMujRgYG/2WfOROLJHJLMfse5iww=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=U+41eWABF84TsEVNBKAWTk6tTOMCAGEmaM5iXWsUXyh4Xl9WYY2dkOccr9kH72WsY j1TZ0AYcZEHNuYdIf5ZscFBVAepdHnorSgJi1tP8WmgvaBSWjhIhbgIlp3QFUVy9sg fJ4oexulhr06wvZEhYkU8Cii5Xo/X0To2xKW1980= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Brian Johannesmeyer , Jakob Koschel Subject: [PATCH 4.9 22/34] vt_ioctl: fix array_index_nospec in vt_setactivate Date: Mon, 14 Feb 2022 10:25:48 +0100 Message-Id: <20220214092446.662947556@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220214092445.946718557@linuxfoundation.org> References: <20220214092445.946718557@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jakob Koschel commit 61cc70d9e8ef5b042d4ed87994d20100ec8896d9 upstream. array_index_nospec ensures that an out-of-bounds value is set to zero on the transient path. Decreasing the value by one afterwards causes a transient integer underflow. vsa.console should be decreased first and then sanitized with array_index_nospec. Kasper Acknowledgements: Jakob Koschel, Brian Johannesmeyer, Kaveh Razavi, Herbert Bos, Cristiano Giuffrida from the VUSec group at VU Amsterdam. Co-developed-by: Brian Johannesmeyer Signed-off-by: Brian Johannesmeyer Signed-off-by: Jakob Koschel Link: https://lore.kernel.org/r/20220127144406.3589293-1-jakobkoschel@gmail.com Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/tty/vt/vt_ioctl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/tty/vt/vt_ioctl.c +++ b/drivers/tty/vt/vt_ioctl.c @@ -718,9 +718,9 @@ int vt_ioctl(struct tty_struct *tty, if (vsa.console == 0 || vsa.console > MAX_NR_CONSOLES) ret = -ENXIO; else { - vsa.console = array_index_nospec(vsa.console, - MAX_NR_CONSOLES + 1); vsa.console--; + vsa.console = array_index_nospec(vsa.console, + MAX_NR_CONSOLES); console_lock(); ret = vc_allocate(vsa.console); if (ret == 0) {