linux-kernel - [PATCH 4.9 118/128] kernel/cpu_pm: Fix uninitted local in cpu

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Date:   Fri, 19 Jun 2020 16:33:32 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Stephen Boyd <swboyd@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Subject: [PATCH 4.9 118/128] kernel/cpu_pm: Fix uninitted local in cpu_pm

From: Douglas Anderson <dianders@...omium.org>

commit b5945214b76a1f22929481724ffd448000ede914 upstream.

cpu_pm_notify() is basically a wrapper of notifier_call_chain().
notifier_call_chain() doesn't initialize *nr_calls to 0 before it
starts incrementing it--presumably it's up to the callers to do this.

Unfortunately the callers of cpu_pm_notify() don't init *nr_calls.
This potentially means you could get too many or two few calls to
CPU_PM_ENTER_FAILED or CPU_CLUSTER_PM_ENTER_FAILED depending on the
luck of the stack.

Let's fix this.

Fixes: ab10023e0088 ("cpu_pm: Add cpu power management notifiers")
Cc: stable@...r.kernel.org
Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Reviewed-by: Stephen Boyd <swboyd@...omium.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Douglas Anderson <dianders@...omium.org>
Link: https://lore.kernel.org/r/20200504104917.v6.3.I2d44fc0053d019f239527a4e5829416714b7e299@changeid
Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 kernel/cpu_pm.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/kernel/cpu_pm.c
+++ b/kernel/cpu_pm.c
@@ -97,7 +97,7 @@ EXPORT_SYMBOL_GPL(cpu_pm_unregister_noti
  */
 int cpu_pm_enter(void)
 {
-	int nr_calls;
+	int nr_calls = 0;
 	int ret = 0;

 	read_lock(&cpu_pm_notifier_lock);
@@ -156,7 +156,7 @@ EXPORT_SYMBOL_GPL(cpu_pm_exit);
  */
 int cpu_cluster_pm_enter(void)
 {
-	int nr_calls;
+	int nr_calls = 0;
 	int ret = 0;

 	read_lock(&cpu_pm_notifier_lock);