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 C62BBC48BD5 for ; Tue, 25 Jun 2019 16:23:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9B154208E3 for ; Tue, 25 Jun 2019 16:23:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ti3NlNQ6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728694AbfFYQXP (ORCPT ); Tue, 25 Jun 2019 12:23:15 -0400 Received: from mail-pf1-f194.google.com ([209.85.210.194]:44789 "EHLO mail-pf1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726740AbfFYQXO (ORCPT ); Tue, 25 Jun 2019 12:23:14 -0400 Received: by mail-pf1-f194.google.com with SMTP id t16so9724186pfe.11 for ; Tue, 25 Jun 2019 09:23:14 -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=PEwqdcBJhdsaGNwQ8qE4axyMsE12bW7MvOTK5Jf6qqU=; b=ti3NlNQ62g67PQgPc9j9llrb2zEXYEBG+Q5EGe0fV3A64ndBCBOu3k+b46nE1nbCpG x+/FVoVhF5daJhzBCgl+Ix9APbMaph1HrCt3Bf/ZeN62s5qPQy7UHbFB0DllWPnTx8St T1RZx8QYUJScxpD9lLoL2bj/nS+VJFo/TNS2HIATAURqVW7qZIQEwEfZ4ieRkSv5BQPO gTFuPtKbss9dUwucRDmTxsCnc6sMvO9u2HgBnZzr9quBjJmwTGO6PeixYrOVznfFpCdT 2FXBHwCtSJmw3Zn4rt9xwb1o9/fvdyD0iGh64DpKs9B5rTI/5hTdoHFX/OuLYx++LSc6 CIrg== 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=PEwqdcBJhdsaGNwQ8qE4axyMsE12bW7MvOTK5Jf6qqU=; b=Zlg0e5ZuhR3eQY284pFpjAndvA6qbZHCp+hGZeHIkBUIsEkX35Q+jD7OdvC7lZtYSj nHM2ZofykHDk3HW8ijAgkR0nQ8YyIoAR/dQ1cLXEFM0/UoyUUqCZBBjcuep/MLOsu8aG BVeFP7byc9mFw3Wxx5kPOJIlcAu8LHNEQNDFW9QVGm8xp/LFkX4MJlwu+RKstC7b/mrQ /fR1J+5y6l2qe9D51UvUFFg3J+mablgdhi1L7Yozs2IhT1QQAyggZN/TPXQFWARnQUW4 asWwGHOHi+TLHn1bk623PdAgdEWV46DizgDLMUE2gGsufVpDQXaLUWHMy7HSfUgvJZ8N Tv+g== X-Gm-Message-State: APjAAAU1oKIdPl8tVDM8/PIO1Y4RaiuIX7EpB80YaddtcMQ/vUCVzrZt 3QHKqjxelXRoFQ7TxmwgJiU= X-Google-Smtp-Source: APXvYqwFffUXMloGSwcQ0uCKL1gdoNJnYRtkhQmJNUhI61gpurLfOgWdCOFsCrgpRaSBy+4lHau6kA== X-Received: by 2002:a17:90a:b00b:: with SMTP id x11mr33213904pjq.120.1561479794311; Tue, 25 Jun 2019 09:23:14 -0700 (PDT) Received: from tom-pc.ipads-lab.se.sjtu.edu.cn ([202.120.40.82]) by smtp.gmail.com with ESMTPSA id w132sm16436090pfd.78.2019.06.25.09.23.10 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 25 Jun 2019 09:23:13 -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 v2] x86/tls: Fix possible spectre-v1 in do_get_thread_area() Date: Wed, 26 Jun 2019 00:22:59 +0800 Message-Id: <1561479779-6660-1-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 | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/tls.c b/arch/x86/kernel/tls.c index a5b802a..424cff5 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 +229,9 @@ 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; + + fill_user_desc(&info, idx, &p->thread.tls_array[index]); if (copy_to_user(u_info, &info, sizeof(info))) return -EFAULT; -- 2.7.4