From: daniel.starke@xxxxxxxxxxx <daniel.starke@xxxxxxxxxxx>
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: e1eaea46bb40 ("tty: n_gsm line discipline")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Daniel Starke <daniel.starke@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220218073123.2121-3-daniel.starke@xxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/n_gsm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -1518,7 +1518,7 @@ static void gsm_dlci_t1(struct timer_lis
dlci->mode = DLCI_MODE_ADM;
gsm_dlci_open(dlci);
} else {
- gsm_dlci_close(dlci);
+ gsm_dlci_begin_close(dlci); /* prevent half open link */
}
break;
