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Subject[PATCH]cpuidle: preventive check in cpuidle_select against crash
When selecting the idle state using cpuidle_select, there is no
check on cpuidle_curr_governor. In cpuidle_switch_governor,
cpuidle_currr_governor can be set to NULL to specify "disabled".

Since cpuidle_select cannot return negative value, it has to return 0
in case of error. Printing logs and returning can help in debugging and
preventing possible kernel crash scenarios.

Signed-off-by: Gaurav Jindal<gauravjindal1104@gmail.com>

---

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 68a1682..bf08e3a 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -268,6 +268,19 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
*/
int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
{
+
+ /* Since negative return is not allowed
+ * we have to return 0 even if the
+ * framework cannot select the idle state
+ */
+ if (!cpuidle_curr_governor) {
+ pr_err("idle governor is disabled\n");
+ return 0;
+ }
+ if (!cpuidle_curr_governor->select) {
+ pr_err("idle governor select is NULL\n");
+ return 0;
+ }
return cpuidle_curr_governor->select(drv, dev);
}
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