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

[ Upstream commit 42bcaacae924bf18ae387c3f78c202df0b739292 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/media/cec/cec-api.c b/drivers/media/cec/cec-api.c
index ed75636a6fb34e413aa50dc06cc9d1eda2a033d8..90e90234f5bd8f29ad1d87cc04efa3086dfa4ac0 100644 (file)
--- a/drivers/media/cec/cec-api.c
+++ b/drivers/media/cec/cec-api.c
@@ -652,6 +652,8 @@ static int cec_release(struct inode *inode, struct file *filp)
                list_del(&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);
@@ -669,6 +671,7 @@ static int cec_release(struct inode *inode, struct file *filp)
                        kfree(entry);
                }
        }
+       mutex_unlock(&fh->lock);
        kfree(fh);
 
        cec_put_device(devnode);