media: cec: cec-api: add locking in cec_release()

When cec_release() uses fh->msgs it has to take fh->lock,
otherwise the list can get corrupted.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reported-by: Yang, Chenyuan <cy54@illinois.edu>
Closes: https://lore.kernel.org/linux-media/PH7PR11MB57688E64ADE4FE82E658D86DA09EA@PH7PR11MB5768.namprd11.prod.outlook.com/
Fixes: ca684386e6e2 ("[media] cec: add HDMI CEC framework (api)")
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

diff --git a/drivers/media/cec/core/cec-api.c b/drivers/media/cec/core/cec-api.c
index 67dc79ef170506fecf666e8d2fefc6ae33b7ca45..d64bb716f9c68bc04fd3730788472a9c9dcdc1f4 100644 (file)
--- a/drivers/media/cec/core/cec-api.c
+++ b/drivers/media/cec/core/cec-api.c
@@ -664,6 +664,8 @@ static int cec_release(struct inode *inode, struct file *filp)
                list_del_init(&data->xfer_list);
        }
        mutex_unlock(&adap->lock);
+
+       mutex_lock(&fh->lock);
        while (!list_empty(&fh->msgs)) {
                struct cec_msg_entry *entry =
                        list_first_entry(&fh->msgs, struct cec_msg_entry, list);
@@ -681,6 +683,7 @@ static int cec_release(struct inode *inode, struct file *filp)
                        kfree(entry);
                }
        }
+       mutex_unlock(&fh->lock);
        kfree(fh);
 
        cec_put_device(devnode);