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Subject[PATCH 1/2] devfreq: fix use after free in devfreq_remove_device
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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>
---
drivers/devfreq/devfreq.c | 8 ++++++--
1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index d065925..59d24e9 100644
--- 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;
--
1.7.5.4




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