From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-bl2nam02on0139.outbound.protection.outlook.com ([104.47.38.139]:31232 "EHLO NAM02-BL2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729831AbeIXUwR (ORCPT ); Mon, 24 Sep 2018 16:52:17 -0400 From: Sasha Levin To: "stable@vger.kernel.org" , "linux-kernel@vger.kernel.org" CC: Sudeep Holla , Olof Johansson , Sasha Levin Subject: [PATCH AUTOSEL 4.18 75/76] firmware: arm_scmi: fix divide by zero when sustained_perf_level is zero Date: Mon, 24 Sep 2018 14:48:45 +0000 Message-ID: <20180924144751.164410-74-alexander.levin@microsoft.com> References: <20180924144751.164410-1-alexander.levin@microsoft.com> In-Reply-To: <20180924144751.164410-1-alexander.levin@microsoft.com> Content-Language: en-US Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org List-ID: From: Sudeep Holla [ Upstream commit 96d529bac562574600eda85726fcfa3eef6dde8e ] Firmware can provide zero as values for sustained performance level and corresponding sustained frequency in kHz in order to hide the actual frequencies and provide only abstract values. It may endup with divide by zero scenario resulting in kernel panic. Let's set the multiplication factor to one if either one or both of them (sustained_perf_level and sustained_freq) are set to zero. Fixes: a9e3fbfaa0ff ("firmware: arm_scmi: add initial support for performan= ce protocol") Reported-by: Ionela Voinescu Signed-off-by: Sudeep Holla Signed-off-by: Olof Johansson Signed-off-by: Sasha Levin --- drivers/firmware/arm_scmi/perf.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/p= erf.c index 2a219b1261b1..49cb74f54a10 100644 --- a/drivers/firmware/arm_scmi/perf.c +++ b/drivers/firmware/arm_scmi/perf.c @@ -166,7 +166,13 @@ scmi_perf_domain_attributes_get(const struct scmi_hand= le *handle, u32 domain, le32_to_cpu(attr->sustained_freq_khz); dom_info->sustained_perf_level =3D le32_to_cpu(attr->sustained_perf_level); - dom_info->mult_factor =3D (dom_info->sustained_freq_khz * 1000) / + if (!dom_info->sustained_freq_khz || + !dom_info->sustained_perf_level) + /* CPUFreq converts to kHz, hence default 1000 */ + dom_info->mult_factor =3D 1000; + else + dom_info->mult_factor =3D + (dom_info->sustained_freq_khz * 1000) / dom_info->sustained_perf_level; memcpy(dom_info->name, attr->name, SCMI_MAX_STR_SIZE); } --=20 2.17.1