Discussion:
[PATCH] cpufreq: powernv: Fix frame-size-overflow in powernv_cpufreq_work_fn
(too old to reply)
Pratik Rajesh Sampat
2020-03-16 13:57:43 UTC
Permalink
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 <***@linux.ibm.com>
---
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
Daniel Axtens
2020-03-17 22:30:39 UTC
Permalink
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 <***@axtens.net>

Regards,
Daniel
Post by Pratik Rajesh Sampat
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")
---
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);
}
put_online_cpus();
--
2.24.1
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