cpuidle: psci: Fix potential access to unmapped memory

Commit Message

Ulf Hansson Oct. 9, 2019, 6:16 p.m. UTC

When the WFI state have been selected, the in-parameter idx to
psci_enter_idle_state() is zero. In this case, we must not index the state
array as "state[idx - 1]", as it means accessing data outside the array.
Fix the bug by pre-checking if idx is zero.

Fixes: 9ffeb6d08c3a ("PSCI: cpuidle: Refactor CPU suspend power_state parameter handling")
Signed-off-by: Ulf Hansson <[e-mail]>
---
 drivers/cpuidle/cpuidle-psci.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Patch

diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c
index f3c1a2396f98..2e91c8d6c211 100644
--- a/drivers/cpuidle/cpuidle-psci.c
+++ b/drivers/cpuidle/cpuidle-psci.c
@@ -27,10 +27,10 @@  static DEFINE_PER_CPU_READ_MOSTLY(u32 *, psci_power_state);
 static int psci_enter_idle_state(struct cpuidle_device *dev,
 				struct cpuidle_driver *drv, int idx)
 {
-	u32 *state = __this_cpu_read(psci_power_state);
+	u32 *states = __this_cpu_read(psci_power_state);
+	u32 state = idx ? states[idx - 1] : 0;
 
-	return CPU_PM_CPU_IDLE_ENTER_PARAM(psci_cpu_suspend_enter,
-					   idx, state[idx - 1]);
+	return CPU_PM_CPU_IDLE_ENTER_PARAM(psci_cpu_suspend_enter, idx, state);
 }
 
 static struct cpuidle_driver psci_idle_driver __initdata = {