PM / devfreq: fix use after free in devfreq_remove_device

In devfreq_remove_device, calling _remove_devfreq will also free devfreq.
Don't dereference devfreq->governor->no_central_polling after _remove_devfreq.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index d0659253387a3ebb7c7d624df03171427246a407..59d24e9cb8c512a949a24803c5bf11a143fc649d 100644 (file)
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -418,10 +418,14 @@ out:
  */
 int devfreq_remove_device(struct devfreq *devfreq)
 {
+       bool central_polling;
+
        if (!devfreq)
                return -EINVAL;
 
-       if (!devfreq->governor->no_central_polling) {
+       central_polling = !devfreq->governor->no_central_polling;
+
+       if (central_polling) {
                mutex_lock(&devfreq_list_lock);
                while (wait_remove_device == devfreq) {
                        mutex_unlock(&devfreq_list_lock);
@@ -433,7 +437,7 @@ int devfreq_remove_device(struct devfreq *devfreq)
        mutex_lock(&devfreq->lock);
        _remove_devfreq(devfreq, false); /* it unlocks devfreq->lock */
 
-       if (!devfreq->governor->no_central_polling)
+       if (central_polling)
                mutex_unlock(&devfreq_list_lock);
 
        return 0;