Commit c03a4958 authored Feb 17, 2022 by daniel.starke@siemens.com Committed by Greg Kroah-Hartman Mar 02, 2022

tty: n_gsm: fix proper link termination after failed open



commit e3b7468f082d106459e86e8dc6fb9bdd65553433 upstream.

Trying to open a DLCI by sending a SABM frame may fail with a timeout.
The link is closed on the initiator side without informing the responder
about this event. The responder assumes the link is open after sending a
UA frame to answer the SABM frame. The link gets stuck in a half open
state.

This patch fixes this by initiating the proper link termination procedure
after link setup timeout instead of silently closing it down.

Fixes: e1eaea46 ("tty: n_gsm line discipline")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220218073123.2121-3-daniel.starke@siemens.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 912144e8

drivers/tty/n_gsm.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1490,7 +1490,7 @@ static void gsm_dlci_t1(struct timer_list *t)
		dlci->mode = DLCI_MODE_ADM;
		gsm_dlci_open(dlci);
		} else {
		gsm_dlci_close(dlci);
		gsm_dlci_begin_close(dlci); /* prevent half open link */
		}

		break;