* [PATCH v2] cpufreq: s3c: avoid use after free issue in xxx_cpufreq_reboot_notifier_evt()
@ 2020-01-06 9:44 qiwuchen55
2020-01-07 5:31 ` Viresh Kumar
0 siblings, 1 reply; 3+ messages in thread
From: qiwuchen55 @ 2020-01-06 9:44 UTC (permalink / raw)
To: kgene, krzk, rjw, viresh.kumar
Cc: linux-arm-kernel, linux-samsung-soc, linux-pm, chenqiwu
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>
---
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
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH v2] cpufreq: s3c: avoid use after free issue in xxx_cpufreq_reboot_notifier_evt()
2020-01-06 9:44 [PATCH v2] cpufreq: s3c: avoid use after free issue in xxx_cpufreq_reboot_notifier_evt() qiwuchen55
@ 2020-01-07 5:31 ` Viresh Kumar
2020-01-07 7:50 ` chenqiwu
0 siblings, 1 reply; 3+ messages in thread
From: Viresh Kumar @ 2020-01-07 5:31 UTC (permalink / raw)
To: qiwuchen55
Cc: kgene, krzk, rjw, linux-arm-kernel, linux-samsung-soc, linux-pm,
chenqiwu
On 06-01-20, 17:44, qiwuchen55@gmail.com wrote:
> 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.
Again, the subject and description are incorrect here. This isn't a user after
free problem as we were already calling cpufreq_cpu_get(). The problem was that
the balancing of refcount wasn't done properly.
> Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
> ---
> 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
--
viresh
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH v2] cpufreq: s3c: avoid use after free issue in xxx_cpufreq_reboot_notifier_evt()
2020-01-07 5:31 ` Viresh Kumar
@ 2020-01-07 7:50 ` chenqiwu
0 siblings, 0 replies; 3+ messages in thread
From: chenqiwu @ 2020-01-07 7:50 UTC (permalink / raw)
To: Viresh Kumar
Cc: kgene, krzk, rjw, linux-arm-kernel, linux-samsung-soc, linux-pm,
chenqiwu
On Tue, Jan 07, 2020 at 11:01:47AM +0530, Viresh Kumar wrote:
> On 06-01-20, 17:44, qiwuchen55@gmail.com wrote:
> > 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.
>
> Again, the subject and description are incorrect here. This isn't a user after
> free problem as we were already calling cpufreq_cpu_get(). The problem was that
> the balancing of refcount wasn't done properly.
>
>
Yeah, I will rewrite the title and commit message, and resend this as
patch v3.
Thanks!
> > Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
> > ---
> > 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
>
> --
> viresh
--
Qiwu
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-01-06 9:44 [PATCH v2] cpufreq: s3c: avoid use after free issue in xxx_cpufreq_reboot_notifier_evt() qiwuchen55
2020-01-07 5:31 ` Viresh Kumar
2020-01-07 7:50 ` chenqiwu
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