From: Daniel Starke Date: Fri, 1 Jul 2022 12:23:32 +0000 (+0200) Subject: tty: n_gsm: fix resource allocation order in gsm_activate_mux() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=e46bc8cacdb6d409303d9178ac56e927e3b2f002;p=linux.git 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 --- diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 23fcb34240acc..b5ce10b0656f4 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;