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=-8.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 44A8BC072B5 for ; Fri, 24 May 2019 11:45:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 10C912168B for ; Fri, 24 May 2019 11:45:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="X5eBh8Hw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391137AbfEXLp0 (ORCPT ); Fri, 24 May 2019 07:45:26 -0400 Received: from mail-pl1-f194.google.com ([209.85.214.194]:36824 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390743AbfEXLpZ (ORCPT ); Fri, 24 May 2019 07:45:25 -0400 Received: by mail-pl1-f194.google.com with SMTP id d21so4091451plr.3 for ; Fri, 24 May 2019 04:45:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=pThOH74d8lQhRMWxtImQn30Cs54Ck/famShCD5k4u9k=; b=X5eBh8HwaH2kevrFZ4TlTPyn6cWvSzx5HtglUCrryy8Wl14EeYfGa5fds8VoZdWH2Q Y5IboCDaK7hJmohhGNaA+8VHgKE08RmVIXejy5dDu6ybTieN93D3+YPvD1Q/cSDsmxTr IjUlcOW1i4Ifo4OPnkiLTM2xonIRh0sx7ke8DZxYFFUW6FW9O/kRjSSxWF9nlqS/pHKa KEsST7jVvik6X2s0l44VmZvevQUcM3Ws+Lix+L+pTz23y+ITtrxMjbiNQ4KM6+IVXj3M SOAscoCG9w41UaSh1UZJcrSAUviHk07oDBzrLa0Kx29mlhRRBM6OM/UO8fblXJcOwL3t P5Tw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=pThOH74d8lQhRMWxtImQn30Cs54Ck/famShCD5k4u9k=; b=W+CPefY/RI4qRqOXu7nlLUQazddPI7oJxDgPEX8DAmSAgiLbHtrYX2iLvdVbZMvY5S AqviyAAHDyt2uc1563UrxUo6KUdz+jSyFY+M5UiC2ENPQXKxorRpy5PMqr77cvG6oG4E Beqi2trTdVXKLXSW/37K0AAaYCd3CthRYXcW5xOEGxfo86Tjlv+LCyCfHxJVZ8kgBtU6 7IYlj0TMetnCpLNAEuT0mlOjeK8Rz873wWq+906cLfApUeUTLTPHRmDgJmifm3caSnpS atKc3CmNIlR6kTu5qQGpFNuIfOZLm894MuKLz2TsWqAgGVv/F32BEKAZEYQ2bnWHKRYi 61hw== X-Gm-Message-State: APjAAAVgVTWdx2DF4iMbZOLFL/V/zK9FDl7lTU4tNFc4ft4bmcnGILBU keFfWpd2iEtkc8e663iwcnY= X-Google-Smtp-Source: APXvYqze+RRkwrHQveGrS6259imBjCp9OcLJ94OtEeaVUC5RKh+JfSsqH5PZudihTnQO6ZBKLjuohA== X-Received: by 2002:a17:902:b084:: with SMTP id p4mr35671110plr.59.1558698325354; Fri, 24 May 2019 04:45:25 -0700 (PDT) Received: from tom-pc.ipads-lab.se.sjtu.edu.cn ([202.120.40.82]) by smtp.gmail.com with ESMTPSA id n27sm5688233pfb.129.2019.05.24.04.45.21 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 24 May 2019 04:45:24 -0700 (PDT) From: Dianzhang Chen To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de Cc: hpa@zytor.com, x86@kernel.org, linux-kernel@vger.kernel.org, Dianzhang Chen Subject: [PATCH] x86: fix possible spectre-v1 in do_get_thread_area() Date: Fri, 24 May 2019 19:45:12 +0800 Message-Id: <1558698312-5716-1-git-send-email-dianzhangchen0@gmail.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The idx in do_get_thread_area() is controlled by userspace via syscall: ptrace(defined in kernel/ptrace.c), hence leading to a potential exploitation of the Spectre variant 1 vulnerability. The idx can be controlled from: ptrace -> arch_ptrace -> do_get_thread_area. Fix this by sanitizing idx before using it to index p->thread.tls_array. Signed-off-by: Dianzhang Chen --- arch/x86/kernel/tls.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/tls.c b/arch/x86/kernel/tls.c index a5b802a..e3dc05b 100644 --- a/arch/x86/kernel/tls.c +++ b/arch/x86/kernel/tls.c @@ -5,6 +5,7 @@ #include #include #include +#include #include #include @@ -220,15 +221,19 @@ int do_get_thread_area(struct task_struct *p, int idx, struct user_desc __user *u_info) { struct user_desc info; + int index = idx - GDT_ENTRY_TLS_MIN; if (idx == -1 && get_user(idx, &u_info->entry_number)) return -EFAULT; - if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) + if (index < 0 || index > GDT_ENTRY_TLS_MAX - GDT_ENTRY_TLS_MIN) return -EINVAL; + index = array_index_nospec(index, + GDT_ENTRY_TLS_MAX - GDT_ENTRY_TLS_MIN + 1); + fill_user_desc(&info, idx, - &p->thread.tls_array[idx - GDT_ENTRY_TLS_MIN]); + &p->thread.tls_array[index]); if (copy_to_user(u_info, &info, sizeof(info))) return -EFAULT; -- 2.7.4