[IRDA]: Fix rfcomm use-after-free

Adrian Bunk wrote:
> 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@holtmann.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 2 deletions

diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index 23ba61a13bdd..22a832098d44 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;