This is a note to let you know that I've just added the patch titled
tty: n_gsm: fix resource allocation order in gsm_activate_mux()
to the 5.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tty-n_gsm-fix-resource-allocation-order-in-gsm_activ.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 83a8d3bf624e92e0c2825cfd0fa5828785f3cb91
Author: Daniel Starke <daniel.starke@xxxxxxxxxxx>
Date: Fri Jul 1 14:23:32 2022 +0200
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 <daniel.starke@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220701122332.2039-2-daniel.starke@xxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index ab7765afab86..17927163790e 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -2501,6 +2501,10 @@ 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);
@@ -2517,9 +2521,6 @@ 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;
