[PATCH] cpufreq: powernv: Fix frame-size-overflow in powernv_cpufreq_work_fn

The patch avoids allocating cpufreq_policy on stack hence fixing frame
size overflow in 'powernv_cpufreq_work_fn'

Fixes: 227942809b52 ("cpufreq: powernv: Restore cpu frequency to policy->cur on unthrottling")
Signed-off-by: Pratik Rajesh Sampat <redacted>
---
 drivers/cpufreq/powernv-cpufreq.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index 56f4bc0d209e..20ee0661555a 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c

@@ -902,6 +902,7 @@ static struct notifier_block powernv_cpufreq_reboot_nb = {
 void powernv_cpufreq_work_fn(struct work_struct *work)
 {
 	struct chip *chip = container_of(work, struct chip, throttle);
+	struct cpufreq_policy *policy;
 	unsigned int cpu;
 	cpumask_t mask;
 

@@ -916,12 +917,14 @@ void powernv_cpufreq_work_fn(struct work_struct *work)
 	chip->restore = false;
 	for_each_cpu(cpu, &mask) {
 		int index;
-		struct cpufreq_policy policy;
 
-		cpufreq_get_policy(&policy, cpu);
-		index = cpufreq_table_find_index_c(&policy, policy.cur);
-		powernv_cpufreq_target_index(&policy, index);
-		cpumask_andnot(&mask, &mask, policy.cpus);
+		policy = cpufreq_cpu_get(cpu);
+		if (!policy)
+			continue;
+		index = cpufreq_table_find_index_c(policy, policy->cur);
+		powernv_cpufreq_target_index(policy, index);
+		cpumask_andnot(&mask, &mask, policy->cpus);
+		cpufreq_cpu_put(policy);
 	}
 out:
 	put_online_cpus();

-- 
2.24.1

Hi Pratik,

Thanks.

I have checked:

 - for matching puts/gets
 - that all the '.' to '->' conversions, aud uses of '&' check out
 - that the Snowpatch checks pass (https://patchwork.ozlabs.org/patch/1255580/)

On that basis:

Reviewed-by: Daniel Axtens <redacted>

Regards,
Daniel

On Monday, March 16, 2020 2:57:43 PM CET Pratik Rajesh Sampat wrote:

The patch avoids allocating cpufreq_policy on stack hence fixing frame
size overflow in 'powernv_cpufreq_work_fn'

Fixes: 227942809b52 ("cpufreq: powernv: Restore cpu frequency to policy->cur on unthrottling")
Signed-off-by: Pratik Rajesh Sampat <redacted>

Any objections or concerns here?

If not, I'll queue it up.

On Mon, Mar 16, 2020 at 07:27:43PM +0530, Pratik Rajesh Sampat wrote:

The patch avoids allocating cpufreq_policy on stack hence fixing frame
size overflow in 'powernv_cpufreq_work_fn'

Thanks for fixing this.

Fixes: 227942809b52 ("cpufreq: powernv: Restore cpu frequency to policy->cur on unthrottling")
Signed-off-by: Pratik Rajesh Sampat <redacted>

Reviewed-by: Gautham R. Shenoy <redacted>

"Rafael J. Wysocki" [off-list ref] writes:

On Monday, March 16, 2020 2:57:43 PM CET Pratik Rajesh Sampat wrote:

quoted

The patch avoids allocating cpufreq_policy on stack hence fixing frame
size overflow in 'powernv_cpufreq_work_fn'

Fixes: 227942809b52 ("cpufreq: powernv: Restore cpu frequency to policy->cur on unthrottling")
Signed-off-by: Pratik Rajesh Sampat <redacted>

Any objections or concerns here?

If not, I'll queue it up.

I have it in my testing branch, but if you pick it up I can drop it.

cheers

quoted

diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index 56f4bc0d209e..20ee0661555a 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c

@@ -902,6 +902,7 @@ static struct notifier_block powernv_cpufreq_reboot_nb = {
 void powernv_cpufreq_work_fn(struct work_struct *work)
 {
 	struct chip *chip = container_of(work, struct chip, throttle);
+	struct cpufreq_policy *policy;
 	unsigned int cpu;
 	cpumask_t mask;
 

@@ -916,12 +917,14 @@ void powernv_cpufreq_work_fn(struct work_struct *work)
 	chip->restore = false;
 	for_each_cpu(cpu, &mask) {
 		int index;
-		struct cpufreq_policy policy;
 
-		cpufreq_get_policy(&policy, cpu);
-		index = cpufreq_table_find_index_c(&policy, policy.cur);
-		powernv_cpufreq_target_index(&policy, index);
-		cpumask_andnot(&mask, &mask, policy.cpus);
+		policy = cpufreq_cpu_get(cpu);
+		if (!policy)
+			continue;
+		index = cpufreq_table_find_index_c(policy, policy->cur);
+		powernv_cpufreq_target_index(policy, index);
+		cpumask_andnot(&mask, &mask, policy->cpus);
+		cpufreq_cpu_put(policy);
 	}
 out:
 	put_online_cpus();

On Tuesday, March 24, 2020 7:34:56 AM CET Michael Ellerman wrote:

"Rafael J. Wysocki" [off-list ref] writes:

quoted

On Monday, March 16, 2020 2:57:43 PM CET Pratik Rajesh Sampat wrote:

quoted

The patch avoids allocating cpufreq_policy on stack hence fixing frame
size overflow in 'powernv_cpufreq_work_fn'

Fixes: 227942809b52 ("cpufreq: powernv: Restore cpu frequency to policy->cur on unthrottling")
Signed-off-by: Pratik Rajesh Sampat <redacted>

Any objections or concerns here?

If not, I'll queue it up.

I have it in my testing branch,

Great!

but if you pick it up I can drop it.

Let it go in through your tree.

Cheers!

On Mon, 2020-03-16 at 13:57:43 UTC, Pratik Rajesh Sampat wrote:

The patch avoids allocating cpufreq_policy on stack hence fixing frame
size overflow in 'powernv_cpufreq_work_fn'

Fixes: 227942809b52 ("cpufreq: powernv: Restore cpu frequency to policy->cur on unthrottling")
Signed-off-by: Pratik Rajesh Sampat <redacted>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/d95fe371ecd28901f11256c610b988ed44e36ee2

cheers