From e46bc8cacdb6d409303d9178ac56e927e3b2f002 Mon Sep 17 00:00:00 2001 From: Daniel Starke Date: Fri, 1 Jul 2022 14:23:32 +0200 Subject: [PATCH] tty: n_gsm: fix resource allocation order in gsm_activate_mux() [ Upstream commit 7349660438603ed19282e75949561406531785a5 ] 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: e1eaea46bb40 ("tty: n_gsm line discipline") Signed-off-by: Daniel Starke Link: https://lore.kernel.org/r/20220701122332.2039-2-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/n_gsm.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 23fcb342..b5ce10b 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -2435,6 +2435,10 @@ 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_waitqueue_head(&gsm->event); @@ -2450,9 +2454,6 @@ 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; -- 2.7.4