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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 00D0FCA9EBC for ; Fri, 25 Oct 2019 18:08:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CA1122070B for ; Fri, 25 Oct 2019 18:08:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732799AbfJYSIY (ORCPT ); Fri, 25 Oct 2019 14:08:24 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:46838 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731468AbfJYSFp (ORCPT ); Fri, 25 Oct 2019 14:05:45 -0400 Received: from [167.98.27.226] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1iO3xw-0008Ot-Js; Fri, 25 Oct 2019 19:05:36 +0100 Received: from ben by deadeye with local (Exim 4.92.2) (envelope-from ) id 1iO3xv-0001je-Ui; Fri, 25 Oct 2019 19:05:35 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , hpa@zytor.com, "Dianzhang Chen" , "Thomas Gleixner" , bp@alien8.de Date: Fri, 25 Oct 2019 19:03:28 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 27/47] x86/ptrace: Fix possible spectre-v1 in ptrace_get_debugreg() In-Reply-To: X-SA-Exim-Connect-IP: 167.98.27.226 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.76-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Dianzhang Chen commit 31a2fbb390fee4231281b939e1979e810f945415 upstream. The index to access the threads ptrace_bps is controlled by userspace via syscall: sys_ptrace(), hence leading to a potential exploitation of the Spectre variant 1 vulnerability. The index can be controlled from: ptrace -> arch_ptrace -> ptrace_get_debugreg. Fix this by sanitizing the user supplied index before using it access thread->ptrace_bps. Signed-off-by: Dianzhang Chen Signed-off-by: Thomas Gleixner Cc: bp@alien8.de Cc: hpa@zytor.com Link: https://lkml.kernel.org/r/1561476617-3759-1-git-send-email-dianzhangchen0@gmail.com [bwh: Backported to 3.16: fold in fix-up from commit 223cea6a4f05 "Merge branch 'x86-pti-for-linus' of ..."] Signed-off-by: Ben Hutchings --- arch/x86/kernel/ptrace.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -24,6 +24,7 @@ #include #include #include +#include #include #include @@ -707,7 +708,8 @@ static unsigned long ptrace_get_debugreg unsigned long val = 0; if (n < HBP_NUM) { - struct perf_event *bp = thread->ptrace_bps[n]; + int index = array_index_nospec(n, HBP_NUM); + struct perf_event *bp = thread->ptrace_bps[index]; if (bp) val = bp->hw.info.address;