This is a note to let you know that I've just added the patch titled tty: n_gsm: fix DM command to the 4.14-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-dm-command.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 3a5298bef8eb032bfb6c10a00c7427904269535c Author: Daniel Starke <daniel.starke@xxxxxxxxxxx> Date: Thu Jul 7 13:32:21 2022 +0200 tty: n_gsm: fix DM command [ Upstream commit 18a948c7d90995d127785e308fa7b701df4c499f ] n_gsm is based on the 3GPP 07.010 and its newer version is the 3GPP 27.010. See https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=1516 The changes from 07.010 to 27.010 are non-functional. Therefore, I refer to the newer 27.010 here. Chapter 5.3.3 defines the DM response. There exists no DM command. However, the current implementation incorrectly sends DM as command in case of unexpected UIH frames in gsm_queue(). Correct this behavior by always sending DM as response. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Signed-off-by: Daniel Starke <daniel.starke@xxxxxxxxxxx> Link: https://lore.kernel.org/r/20220707113223.3685-2-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 5f5a7ad4c46a..1d50f3ab4e5a 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1906,7 +1906,7 @@ static void gsm_queue(struct gsm_mux *gsm) goto invalid; #endif if (dlci == NULL || dlci->state != DLCI_OPEN) { - gsm_command(gsm, address, DM|PF); + gsm_response(gsm, address, DM|PF); return; } dlci->data(dlci, gsm->buf, gsm->len);