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Subject[PATCH] cpufreq: s3c: avoid use after free issue in xxx_cpufreq_reboot_notifier_evt()
Date
From: chenqiwu <chenqiwu@xiaomi.com>

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 <chenqiwu@xiaomi.com>
---
drivers/cpufreq/s3c2416-cpufreq.c | 11 ++++++++++-
drivers/cpufreq/s5pv210-cpufreq.c | 10 +++++++++-
2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/s3c2416-cpufreq.c b/drivers/cpufreq/s3c2416-cpufreq.c
index 1069103..0f576ba 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 +319,15 @@ 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);
+
+ memset(&policy, 0, sizeof(policy));
+ ret = cpufreq_get_policy(&policy, 0);
+ if (ret < 0) {
+ pr_debug("cpufreq: get no policy for cpu0\n");
+ return NOTIFY_BAD;
+ }
+
+ ret = cpufreq_driver_target(&policy, FREQ_SLEEP, 0);
if (ret < 0)
return NOTIFY_BAD;
}
diff --git a/drivers/cpufreq/s5pv210-cpufreq.c b/drivers/cpufreq/s5pv210-cpufreq.c
index 5d10030..d99b4b1 100644
--- a/drivers/cpufreq/s5pv210-cpufreq.c
+++ b/drivers/cpufreq/s5pv210-cpufreq.c
@@ -555,8 +555,16 @@ static int s5pv210_cpufreq_reboot_notifier_event(struct notifier_block *this,
unsigned long event, void *ptr)
{
int ret;
+ struct cpufreq_policy *policy;

- ret = cpufreq_driver_target(cpufreq_cpu_get(0), SLEEP_FREQ, 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, SLEEP_FREQ, 0);
+ cpufreq_cpu_put(policy);
if (ret < 0)
return NOTIFY_BAD;

--
1.9.1
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