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

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[ 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: e1eaea46bb ("tty: n_gsm line discipline")
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220701122332.2039-2-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Daniel Starke
2022-07-01 14:23:32 +02:00
committed by Greg Kroah-Hartman
parent c9754e10f1
commit e46bc8cacd
1 changed files with 4 additions and 3 deletions
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7
drivers/tty/n_gsm.c
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@@ -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;