Re: net/bluetooth/rfcomm/tty.c: use-after-free

[Marcel Holtmann]

Hi Adrian,

> Commit 8de0a15483b357d0f0b821330ec84d1660cadc4e added the following 
> use-after-free in net/bluetooth/rfcomm/tty.c:
> 
> <--  snip  -->
> 
> ...
> static int rfcomm_dev_add(struct rfcomm_dev_req *req, struct rfcomm_dlc *dlc)
> {
> ...
>         if (IS_ERR(dev->tty_dev)) {
>                 list_del(&dev->list);
>                 kfree(dev);
>                 return PTR_ERR(dev->tty_dev);
>         }
> ...
> 
> <--  snip  -->
> 
> Spotted by the Coverity checker.

really good catch. I fully overlooked that one. The attached patch
should fix it.

Signed-off-by: Marcel Holtmann <marcel@xxxxxxxxxxxx>

Regards

Marcel

diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index 23ba61a..22a8320 100644
--- a/net/bluetooth/rfcomm/tty.c
+++ b/net/bluetooth/rfcomm/tty.c
@@ -267,7 +267,7 @@ static int rfcomm_dev_add(struct rfcomm_dev_req *req, struct rfcomm_dlc *dlc)
 out:
 	write_unlock_bh(&rfcomm_dev_lock);
 
-	if (err) {
+	if (err < 0) {
 		kfree(dev);
 		return err;
 	}
@@ -275,9 +275,10 @@ out:
 	dev->tty_dev = tty_register_device(rfcomm_tty_driver, dev->id, NULL);
 
 	if (IS_ERR(dev->tty_dev)) {
+		err = PTR_ERR(dev->tty_dev);
 		list_del(&dev->list);
 		kfree(dev);
-		return PTR_ERR(dev->tty_dev);
+		return err;
 	}
 
 	return dev->id;