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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 E05FBC3279B for ; Tue, 10 Jul 2018 18:19:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A28D0208E5 for ; Tue, 10 Jul 2018 18:19:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A28D0208E5 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732388AbeGJSSh (ORCPT ); Tue, 10 Jul 2018 14:18:37 -0400 Received: from foss.arm.com ([217.140.101.70]:51614 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732200AbeGJSSh (ORCPT ); Tue, 10 Jul 2018 14:18:37 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 00AD01BB2; Tue, 10 Jul 2018 11:01:32 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 747493F589; Tue, 10 Jul 2018 11:01:30 -0700 (PDT) From: Mark Rutland To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: catalin.marinas@arm.com, christoffer.dall@arm.com, kvmarm@lists.cs.columbia.edu, marc.zyngier@arm.com, mark.rutland@arm.com, will.deacon@arm.com Subject: [PATCH 1/2] arm64: fix possible spectre-v1 write in ptrace_hbp_set_event() Date: Tue, 10 Jul 2018 19:01:22 +0100 Message-Id: <20180710180123.56461-2-mark.rutland@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20180710180123.56461-1-mark.rutland@arm.com> References: <20180710180123.56461-1-mark.rutland@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It's possible for userspace to control idx. Sanitize idx when using it as an array index, to inhibit the potential spectre-v1 write gadget. Found by smatch. Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: Will Deacon --- arch/arm64/kernel/ptrace.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 5c338ce5a7fa..db5440339ab3 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -277,19 +277,22 @@ static int ptrace_hbp_set_event(unsigned int note_type, switch (note_type) { case NT_ARM_HW_BREAK: - if (idx < ARM_MAX_BRP) { - tsk->thread.debug.hbp_break[idx] = bp; - err = 0; - } + if (idx >= ARM_MAX_BRP) + goto out; + idx = array_index_nospec(idx, ARM_MAX_BRP); + tsk->thread.debug.hbp_break[idx] = bp; + err = 0; break; case NT_ARM_HW_WATCH: - if (idx < ARM_MAX_WRP) { - tsk->thread.debug.hbp_watch[idx] = bp; - err = 0; - } + if (idx >= ARM_MAX_WRP) + goto out; + idx = array_index_nospec(idx, ARM_MAX_WRP); + tsk->thread.debug.hbp_watch[idx] = bp; + err = 0; break; } +out: return err; } -- 2.11.0