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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_RED,USER_AGENT_GIT autolearn=unavailable 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 7C765C41519 for ; Mon, 15 Mar 2021 14:33:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 61B9164F00 for ; Mon, 15 Mar 2021 14:33:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239803AbhCOOdH (ORCPT ); Mon, 15 Mar 2021 10:33:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:38284 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232404AbhCOOBU (ORCPT ); Mon, 15 Mar 2021 10:01:20 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4ED4D64F52; Mon, 15 Mar 2021 14:00:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1615816855; bh=heoRBBbg4wXrFA16wBhi5rGQpliksVgEIuFQeZHud0c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dClgpOlXQ1Ss12Bzlq8Sl9Tx8n/NCV0ZZUlGdd/t2urT9JPsLZflayO8hPy+A0mKb mqPENmwil4a7U5YDfp0B3382zcJDi+RG14BeSkKz0/FB/RrIuF0NFmb3dDIY3L8ktl iqZDH21uF3D0Bi8VRVEIeCTsd5oa7QwMtLmlyToA= From: gregkh@linuxfoundation.org To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexey Dobriyan , Linus Torvalds , Sasha Levin Subject: [PATCH 4.19 112/120] prctl: fix PR_SET_MM_AUXV kernel stack leak Date: Mon, 15 Mar 2021 14:57:43 +0100 Message-Id: <20210315135723.655143908@linuxfoundation.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210315135720.002213995@linuxfoundation.org> References: <20210315135720.002213995@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: Greg Kroah-Hartman From: Alexey Dobriyan [ Upstream commit c995f12ad8842dbf5cfed113fb52cdd083f5afd1 ] Doing a prctl(PR_SET_MM, PR_SET_MM_AUXV, addr, 1); will copy 1 byte from userspace to (quite big) on-stack array and then stash everything to mm->saved_auxv. AT_NULL terminator will be inserted at the very end. /proc/*/auxv handler will find that AT_NULL terminator and copy original stack contents to userspace. This devious scheme requires CAP_SYS_RESOURCE. Signed-off-by: Alexey Dobriyan Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- kernel/sys.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sys.c b/kernel/sys.c index baf60a3aa34b..81ed6023d01b 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -2069,7 +2069,7 @@ static int prctl_set_auxv(struct mm_struct *mm, unsigned long addr, * up to the caller to provide sane values here, otherwise userspace * tools which use this vector might be unhappy. */ - unsigned long user_auxv[AT_VECTOR_SIZE]; + unsigned long user_auxv[AT_VECTOR_SIZE] = {}; if (len > sizeof(user_auxv)) return -EINVAL; -- 2.30.1