From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:55552 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730150AbeIXSRM (ORCPT ); Mon, 24 Sep 2018 14:17:12 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mark Rutland , Catalin Marinas , Will Deacon , Sasha Levin Subject: [PATCH 4.14 056/173] arm64: fix possible spectre-v1 write in ptrace_hbp_set_event() Date: Mon, 24 Sep 2018 13:51:30 +0200 Message-Id: <20180924113120.104243611@linuxfoundation.org> In-Reply-To: <20180924113114.334025954@linuxfoundation.org> References: <20180924113114.334025954@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mark Rutland [ Upstream commit 14d6e289a89780377f8bb09de8926d3c62d763cd ] 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 Signed-off-by: Will Deacon Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/ptrace.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -274,19 +274,22 @@ static int ptrace_hbp_set_event(unsigned 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; }