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Mon, 06 Jan 2020 01:44:25 -0800 (PST) From: qiwuchen55@gmail.com To: kgene@kernel.org, krzk@kernel.org, rjw@rjwysocki.net, viresh.kumar@linaro.org Subject: [PATCH v2] cpufreq: s3c: avoid use after free issue in xxx_cpufreq_reboot_notifier_evt() Date: Mon, 6 Jan 2020 17:44:21 +0800 Message-Id: <1578303861-7217-1-git-send-email-qiwuchen55@gmail.com> X-Mailer: git-send-email 1.9.1 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200106_014426_494830_226F9A72 X-CRM114-Status: GOOD ( 12.42 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-samsung-soc@vger.kernel.org, chenqiwu , linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: chenqiwu There is a potential UAF issue in xxx_cpufreq_reboot_notifier_evt() that the cpufreq policy of cpu0 has been released before using it. So we should make a judgement to avoid it. Signed-off-by: chenqiwu --- changes in v2: - use the combination of cpufreq_cpu_get() and cpufreq_cpu_put() instead of cpufreq_get_policy() in s3c2416-cpufreq.c --- drivers/cpufreq/s3c2416-cpufreq.c | 12 +++++++++++- drivers/cpufreq/s5pv210-cpufreq.c | 11 ++++++++++- 2 files changed, 21 insertions(+), 2 deletions(-) diff --git a/drivers/cpufreq/s3c2416-cpufreq.c b/drivers/cpufreq/s3c2416-cpufreq.c index 1069103..f07c5d1 100644 --- a/drivers/cpufreq/s3c2416-cpufreq.c +++ b/drivers/cpufreq/s3c2416-cpufreq.c @@ -304,6 +304,7 @@ static int s3c2416_cpufreq_reboot_notifier_evt(struct notifier_block *this, { struct s3c2416_data *s3c_freq = &s3c2416_cpufreq; int ret; + struct cpufreq_policy *policy; mutex_lock(&cpufreq_lock); @@ -318,7 +319,16 @@ static int s3c2416_cpufreq_reboot_notifier_evt(struct notifier_block *this, */ if (s3c_freq->is_dvs) { pr_debug("cpufreq: leave dvs on reboot\n"); - ret = cpufreq_driver_target(cpufreq_cpu_get(0), FREQ_SLEEP, 0); + + policy = cpufreq_cpu_get(0); + if (!policy) { + pr_debug("cpufreq: get no policy for cpu0\n"); + return NOTIFY_BAD; + } + + ret = cpufreq_driver_target(&policy, FREQ_SLEEP, 0); + cpufreq_cpu_put(policy); + if (ret < 0) return NOTIFY_BAD; } diff --git a/drivers/cpufreq/s5pv210-cpufreq.c b/drivers/cpufreq/s5pv210-cpufreq.c index 5d10030..e84281e 100644 --- a/drivers/cpufreq/s5pv210-cpufreq.c +++ b/drivers/cpufreq/s5pv210-cpufreq.c @@ -555,8 +555,17 @@ static int s5pv210_cpufreq_reboot_notifier_event(struct notifier_block *this, unsigned long event, void *ptr) { int ret; + struct cpufreq_policy *policy; + + policy = cpufreq_cpu_get(0); + if (!policy) { + pr_debug("cpufreq: get no policy for cpu0\n"); + return NOTIFY_BAD; + } + + ret = cpufreq_driver_target(policy, SLEEP_FREQ, 0); + cpufreq_cpu_put(policy); - ret = cpufreq_driver_target(cpufreq_cpu_get(0), SLEEP_FREQ, 0); if (ret < 0) return NOTIFY_BAD; -- 1.9.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel