From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out1-smtp.messagingengine.com ([66.111.4.25]:40533 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727378AbeIGPqg (ORCPT ); Fri, 7 Sep 2018 11:46:36 -0400 Subject: FAILED: patch "[PATCH] cpufreq: governor: Avoid accessing invalid governor_data" failed to apply to 4.9-stable tree To: henry.willard@oracle.com, rafael.j.wysocki@intel.com, stable@vger.kernel.org Cc: From: Date: Fri, 07 Sep 2018 13:06:06 +0200 Message-ID: <153631836692186@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >>From 2a3eb51e30b9ac66fe1b75877627a7e4aaeca24a Mon Sep 17 00:00:00 2001 From: Henry Willard Date: Tue, 14 Aug 2018 17:01:02 -0700 Subject: [PATCH] cpufreq: governor: Avoid accessing invalid governor_data If cppc_cpufreq.ko is deleted at the same time that tuned-adm is changing profiles, there is a small chance that a race can occur between cpufreq_dbs_governor_exit() and cpufreq_dbs_governor_limits() resulting in a system failure when the latter tries to use policy->governor_data that has been freed by the former. This patch uses gov_dbs_data_mutex to synchronize access. Fixes: e788892ba3cc (cpufreq: governor: Get rid of governor events) Signed-off-by: Henry Willard [ rjw: Subject, minor white space adjustment ] Cc: 4.8+ # 4.8+ Signed-off-by: Rafael J. Wysocki diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c index 1d50e97d49f1..6d53f7d9fc7a 100644 --- a/drivers/cpufreq/cpufreq_governor.c +++ b/drivers/cpufreq/cpufreq_governor.c @@ -555,12 +555,20 @@ EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_stop); void cpufreq_dbs_governor_limits(struct cpufreq_policy *policy) { - struct policy_dbs_info *policy_dbs = policy->governor_data; + struct policy_dbs_info *policy_dbs; + + /* Protect gov->gdbs_data against cpufreq_dbs_governor_exit() */ + mutex_lock(&gov_dbs_data_mutex); + policy_dbs = policy->governor_data; + if (!policy_dbs) + goto out; mutex_lock(&policy_dbs->update_mutex); cpufreq_policy_apply_limits(policy); gov_update_sample_delay(policy_dbs, 0); - mutex_unlock(&policy_dbs->update_mutex); + +out: + mutex_unlock(&gov_dbs_data_mutex); } EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_limits);