Commit 73496604 authored by Daniel Starke's avatar Daniel Starke Committed by Greg Kroah-Hartman
Browse files

tty: n_gsm: fix resource allocation order in gsm_activate_mux() 



Within gsm_activate_mux() all timers and locks are initiated before the
actual resource for the control channel is allocated. This can lead to race
conditions.

Allocate the control channel DLCI object first to avoid race conditions.

Fixes: e1eaea46 ("tty: n_gsm line discipline")
Signed-off-by: default avatarDaniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220701122332.2039-2-daniel.starke@siemens.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0af02167

drivers/tty/n_gsm.c

+4 −3
Original line number Diff line number Diff line
@@ -2497,6 +2497,10 @@ static int gsm_activate_mux(struct gsm_mux *gsm) 
	struct gsm_dlci *dlci;

	int ret;



	dlci = gsm_dlci_alloc(gsm, 0);

	if (dlci == NULL)

		return -ENOMEM;



	timer_setup(&gsm->kick_timer, gsm_kick_timer, 0);

	timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0);

	INIT_WORK(&gsm->tx_work, gsmld_write_task);
@@ -2513,9 +2517,6 @@ static int gsm_activate_mux(struct gsm_mux *gsm) 
	if (ret)

		return ret;



	dlci = gsm_dlci_alloc(gsm, 0);

	if (dlci == NULL)

		return -ENOMEM;

	gsm->has_devices = true;

	gsm->dead = false;		/* Tty opens are now permissible */

	return 0;