Linux-Samsung-soc Archive on lore.kernel.org
 help / color / Atom feed
* [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	[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

end of thread, back to index

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
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

Linux-Samsung-soc Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-samsung-soc/0 linux-samsung-soc/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-samsung-soc linux-samsung-soc/ https://lore.kernel.org/linux-samsung-soc \
		linux-samsung-soc@vger.kernel.org
	public-inbox-index linux-samsung-soc

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-samsung-soc


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git