This is a note to let you know that I've just added the patch titled
tty: n_gsm: fix mux activation issues in gsm_config()
to the 5.10-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-mux-activation-issues-in-gsm_config.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From edd5f60c340086891fab094ad61270d6c80f9ca4 Mon Sep 17 00:00:00 2001
From: Daniel Starke <daniel.starke@xxxxxxxxxxx>
Date: Wed, 4 May 2022 10:17:32 +0200
Subject: tty: n_gsm: fix mux activation issues in gsm_config()
From: Daniel Starke <daniel.starke@xxxxxxxxxxx>
commit edd5f60c340086891fab094ad61270d6c80f9ca4 upstream.
The current implementation activates the mux if it was restarted and opens
the control channel if the mux was previously closed and we are now acting
as initiator instead of responder, which is the default setting.
This has two issues.
1) No mux is activated if we keep all default values and only switch to
initiator. The control channel is not allocated but will be opened next
which results in a NULL pointer dereference.
2) Switching the configuration after it was once configured while keeping
the initiator value the same will not reopen the control channel if it was
closed due to parameter incompatibilities. The mux remains dead.
Fix 1) by always activating the mux if it is dead after configuration.
Fix 2) by always opening the control channel after mux activation.
Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Daniel Starke <daniel.starke@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220504081733.3494-2-daniel.starke@xxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/n_gsm.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -2276,6 +2276,7 @@ static void gsm_copy_config_values(struc
static int gsm_config(struct gsm_mux *gsm, struct gsm_config *c)
{
+ int ret = 0;
int need_close = 0;
int need_restart = 0;
@@ -2343,10 +2344,13 @@ static int gsm_config(struct gsm_mux *gs
* FIXME: We need to separate activation/deactivation from adding
* and removing from the mux array
*/
- if (need_restart)
- gsm_activate_mux(gsm);
- if (gsm->initiator && need_close)
- gsm_dlci_begin_open(gsm->dlci[0]);
+ if (gsm->dead) {
+ ret = gsm_activate_mux(gsm);
+ if (ret)
+ return ret;
+ if (gsm->initiator)
+ gsm_dlci_begin_open(gsm->dlci[0]);
+ }
return 0;
}
Patches currently in stable-queue which might be from daniel.starke@xxxxxxxxxxx are
queue-5.10/tty-n_gsm-fix-mux-activation-issues-in-gsm_config.patch
