[PATCH] rapidio: fix possible UAF when kfifo_alloc() fails

[Wang Weiyang]

If kfifo_alloc() fails in mport_cdev_open(), goto err_fifo and just free
priv. But priv is still in the chdev->file_list, then list traversal
may cause UAF. This fixes the following smatch warning:

drivers/rapidio/devices/rio_mport_cdev.c:1930 mport_cdev_open() warn: '&priv->list' not removed from list

Fixes: e8de370188d0 ("rapidio: add mport char device driver")
Signed-off-by: Wang Weiyang <wangweiyang2@xxxxxxxxxx>
---
 drivers/rapidio/devices/rio_mport_cdev.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c
index 3cc83997a1f8..c66b2c552b38 100644
--- a/drivers/rapidio/devices/rio_mport_cdev.c
+++ b/drivers/rapidio/devices/rio_mport_cdev.c
@@ -1930,6 +1930,9 @@ static int mport_cdev_open(struct inode *inode, struct file *filp)
 	filp->private_data = priv;
 	goto out;
 err_fifo:
+	mutex_lock(&chdev->file_mutex);
+	list_del(&priv->list);
+	mutex_unlock(&chdev->file_mutex);
 	kfree(priv);
 out:
 	return ret;
-- 
2.17.1