[PATCH 08/21] TTY: hci_ldisc, remove invalid check in open

[PATCH 08/21] TTY: hci_ldisc, remove invalid check in open

[Jiri Slaby]

hci_ldisc's open checks if tty_struct->disc_data is set. And if so it
returns with an error. But nothing ensures disc_data to be NULL. And
since ld->ops->open shall be called only once, we do not need the
check at all. So remove it.

Note that this is not an issue now, but n_tty will start using the
disc_data pointer and this invalid 'if' would trigger then rendering
TTYs over BT unusable.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: linux-bluetooth@vger.kernel.org
---
 drivers/bluetooth/hci_ldisc.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index c8abce3..ed0fade 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -270,15 +270,10 @@ static int hci_uart_send_frame(struct sk_buff *skb)
  */
 static int hci_uart_tty_open(struct tty_struct *tty)
 {
-	struct hci_uart *hu = (void *) tty->disc_data;
+	struct hci_uart *hu;
 
 	BT_DBG("tty %p", tty);
 
-	/* FIXME: This btw is bogus, nothing requires the old ldisc to clear
-	   the pointer */
-	if (hu)
-		return -EEXIST;
-
 	/* Error if the tty has no write op instead of leaving an exploitable
 	   hole */
 	if (tty->ops->write == NULL)
-- 
1.7.12.3

Re: [PATCH 08/21] TTY: hci_ldisc, remove invalid check in open

[Marcel Holtmann]

Hi Jiri,

> hci_ldisc's open checks if tty_struct->disc_data is set. And if so it
> returns with an error. But nothing ensures disc_data to be NULL. And
> since ld->ops->open shall be called only once, we do not need the
> check at all. So remove it.
> 
> Note that this is not an issue now, but n_tty will start using the
> disc_data pointer and this invalid 'if' would trigger then rendering
> TTYs over BT unusable.
> 
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
> Cc: Marcel Holtmann <marcel@holtmann.org>
> Cc: Gustavo Padovan <gustavo@padovan.org>
> Cc: Johan Hedberg <johan.hedberg@gmail.com>
> Cc: linux-bluetooth@vger.kernel.org
> ---
>  drivers/bluetooth/hci_ldisc.c | 7 +------
>  1 file changed, 1 insertion(+), 6 deletions(-)

Acked-by: Marcel Holtmann <marcel@holtmann.org>

Regards

Marcel