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=-8.6 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 C193CC4646B for ; Wed, 26 Jun 2019 04:50:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 92B082080C for ; Wed, 26 Jun 2019 04:50:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="OAPUke4T" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726486AbfFZEup (ORCPT ); Wed, 26 Jun 2019 00:50:45 -0400 Received: from mail-pl1-f194.google.com ([209.85.214.194]:35030 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725308AbfFZEuo (ORCPT ); Wed, 26 Jun 2019 00:50:44 -0400 Received: by mail-pl1-f194.google.com with SMTP id w24so706104plp.2 for ; Tue, 25 Jun 2019 21:50:44 -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=bCahL/6yT/1jlLN2Hc0XJcKCEaxb5WvlkSRDA5kX+/4=; b=OAPUke4T9v54nrhFW2tatHLdacZ0Uye7TVxCs+d7p+yo74JfnJv9dtk+tlbYWJxoXE TjriPya4ewKp/90t8H+vC4hS6avqmK9LCPVfAg/lZEogepY0axvgqy0k5l6jZ9FWDGuC 9/qde8ajZJB3y8H/SzjpkxT+4tRvsSZ1SAmCKQc2emkm0L3YIQtFBNlPCUPuHZavuXy4 /mlOj6yqBVJw3MbFG1FX4GdJEfzJFumnHen4ALRyzGpcbVHBklInkGhdm7Ch2y9wkm1R GvU+k8q2L6HE2i3zp519K/B3hXizOYLU9SN/GPbVR5PB2YNCxh0tSZxM+ASSPFvjZfTz xCXA== 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=bCahL/6yT/1jlLN2Hc0XJcKCEaxb5WvlkSRDA5kX+/4=; b=YjAxmu8ayiO0MZ7p79xiT8DR+/ODs1f3t4NKQVW8m90TXlV3N2mVnW76P2vMX5sCZu H2bavU2dgJ5CFQO1eZXAY0eFw8UMwnzoV0hVrZwxrzWLUmVC6lmAC3oQV6bYg7HWBhWz uQduB8xtXoQmPEAu0G43hPnYIOJLEJpXP01rUiPqAv2rxU+y5lASpCE4nhHFLqUgd5Ra vc19D35fJ7SkRcnQHb235Vel8vHUszQMJCigetHi60v+bp5B2j0VBeiZoYXg7CE8DerP PzMkptYiz54YQf3xPydmBfF++BwkCWuhBkPTccucY/s26ksYwVKHHN7SvJYJCC5H+rwc VGag== X-Gm-Message-State: APjAAAXHN4Fhq1dqzNNf5MTuh7ehWeLengf44RySJZ5sNVV6SEzSIhLa dVtBCTvFTCu244yvyJP+588= X-Google-Smtp-Source: APXvYqxokN1WtrPa3LegU6W2/R7CM9tiA4NWuHH4O0iUiSukFvA88OneYzZba9NytSu8AonNzOPmtQ== X-Received: by 2002:a17:902:1e6:: with SMTP id b93mr2855318plb.295.1561524644301; Tue, 25 Jun 2019 21:50:44 -0700 (PDT) Received: from tom-pc.ipads-lab.se.sjtu.edu.cn ([202.120.40.82]) by smtp.gmail.com with ESMTPSA id j14sm17601902pfn.120.2019.06.25.21.50.40 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 25 Jun 2019 21:50:43 -0700 (PDT) From: Dianzhang Chen To: tglx@linutronix.de Cc: mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org, linux-kernel@vger.kernel.org, Dianzhang Chen Subject: [PATCH v3] x86/tls: Fix possible spectre-v1 in do_get_thread_area() Date: Wed, 26 Jun 2019 12:50:30 +0800 Message-Id: <1561524630-3642-1-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 index to access the threads tls array is controlled by userspace via syscall: sys_ptrace(), 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..71d3fef 100644 --- a/arch/x86/kernel/tls.c +++ b/arch/x86/kernel/tls.c @@ -5,6 +5,7 @@ #include #include #include +#include #include #include @@ -220,6 +221,7 @@ int do_get_thread_area(struct task_struct *p, int idx, struct user_desc __user *u_info) { struct user_desc info; + int index; if (idx == -1 && get_user(idx, &u_info->entry_number)) return -EFAULT; @@ -227,8 +229,11 @@ int do_get_thread_area(struct task_struct *p, int idx, if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) return -EINVAL; - fill_user_desc(&info, idx, - &p->thread.tls_array[idx - GDT_ENTRY_TLS_MIN]); + index = idx - GDT_ENTRY_TLS_MIN; + index = array_index_nospec(index, + GDT_ENTRY_TLS_MAX - GDT_ENTRY_TLS_MIN + 1); + + fill_user_desc(&info, idx, &p->thread.tls_array[index]); if (copy_to_user(u_info, &info, sizeof(info))) return -EFAULT; -- 2.7.4