2015-12-19 12:54:49

by Javi Merino

Subject: [PATCH] thermal: cpu_cooling: fix out of bounds access in time_in_idle

In __cpufreq_cooling_register() we allocate the arrays for time_in_idle
and time_in_idle_timestamp to be as big as the number of cpus in this
cpufreq device. However, in get_load() we access this array using the
cpu number as index, which can result in an out of bound access.

Index time_in_idle{,_timestamp} using the index in the cpufreq_device's
allowed_cpus mask, as we do for the load_cpu array in
cpufreq_get_requested_power()

Reported-by: Nicolas Boichat <[email protected]>
Cc: Amit Daniel Kachhap <[email protected]>
Cc: Viresh Kumar <[email protected]>
Cc: Zhang Rui <[email protected]>
Cc: Eduardo Valentin <[email protected]>
Signed-off-by: Javi Merino <[email protected]>
---
drivers/thermal/cpu_cooling.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
index e3fbc5a5d88f..bd1bab9eade0 100644
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -377,26 +377,28 @@ static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_device,
* get_load() - get load for a cpu since last updated
* @cpufreq_device: &struct cpufreq_cooling_device for this cpu
* @cpu: cpu number
+ * @cpu_idx: index of the cpu in cpufreq_device->allowed_cpus
*
* Return: The average load of cpu @cpu in percentage since this
* function was last called.
*/
-static u32 get_load(struct cpufreq_cooling_device *cpufreq_device, int cpu)
+static u32 get_load(struct cpufreq_cooling_device *cpufreq_device, int cpu,
+ int cpu_idx)
{
u32 load;
u64 now, now_idle, delta_time, delta_idle;

now_idle = get_cpu_idle_time(cpu, &now, 0);
- delta_idle = now_idle - cpufreq_device->time_in_idle[cpu];
- delta_time = now - cpufreq_device->time_in_idle_timestamp[cpu];
+ delta_idle = now_idle - cpufreq_device->time_in_idle[cpu_idx];
+ delta_time = now - cpufreq_device->time_in_idle_timestamp[cpu_idx];

if (delta_time <= delta_idle)
load = 0;
else
load = div64_u64(100 * (delta_time - delta_idle), delta_time);

- cpufreq_device->time_in_idle[cpu] = now_idle;
- cpufreq_device->time_in_idle_timestamp[cpu] = now;
+ cpufreq_device->time_in_idle[cpu_idx] = now_idle;
+ cpufreq_device->time_in_idle_timestamp[cpu_idx] = now;

return load;
}
@@ -598,7 +600,7 @@ static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
u32 load;

if (cpu_online(cpu))
- load = get_load(cpufreq_device, cpu);
+ load = get_load(cpufreq_device, cpu, i);
else
load = 0;

--
1.9.1

2015-12-21 03:19:46

by Viresh Kumar

Subject: Re: [PATCH] thermal: cpu_cooling: fix out of bounds access in time_in_idle

On 19-12-15, 12:54, Javi Merino wrote:
> In __cpufreq_cooling_register() we allocate the arrays for time_in_idle
> and time_in_idle_timestamp to be as big as the number of cpus in this
> cpufreq device. However, in get_load() we access this array using the
> cpu number as index, which can result in an out of bound access.
>
> Index time_in_idle{,_timestamp} using the index in the cpufreq_device's
> allowed_cpus mask, as we do for the load_cpu array in
> cpufreq_get_requested_power()
>
> Reported-by: Nicolas Boichat <[email protected]>
> Cc: Amit Daniel Kachhap <[email protected]>
> Cc: Viresh Kumar <[email protected]>
> Cc: Zhang Rui <[email protected]>
> Cc: Eduardo Valentin <[email protected]>
> Signed-off-by: Javi Merino <[email protected]>
> ---
> drivers/thermal/cpu_cooling.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)

Acked-by: Viresh Kumar <[email protected]>

--
viresh