--- /dev/null
+From a24b4b2f660b7ddf3f484b37600bba382cb28a9d Mon Sep 17 00:00:00 2001
+From: Daniel Starke <daniel.starke@siemens.com>
+Date: Thu, 14 Apr 2022 02:42:12 -0700
+Subject: tty: n_gsm: fix malformed counter for out of frame data
+
+From: Daniel Starke <daniel.starke@siemens.com>
+
+commit a24b4b2f660b7ddf3f484b37600bba382cb28a9d upstream.
+
+The gsm_mux field 'malformed' represents the number of malformed frames
+received. However, gsm1_receive() also increases this counter for any out
+of frame byte.
+Fix this by ignoring out of frame data for the malformed counter.
+
+Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
+Cc: stable@vger.kernel.org
+Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
+Link: https://lore.kernel.org/r/20220414094225.4527-7-daniel.starke@siemens.com
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/tty/n_gsm.c | 3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+--- a/drivers/tty/n_gsm.c
++++ b/drivers/tty/n_gsm.c
+@@ -1977,7 +1977,8 @@ static void gsm1_receive(struct gsm_mux
+ }
+ /* Any partial frame was a runt so go back to start */
+ if (gsm->state != GSM_START) {
+- gsm->malformed++;
++ if (gsm->state != GSM_SEARCH)
++ gsm->malformed++;
+ gsm->state = GSM_START;
+ }
+ /* A SOF in GSM_START means we are still reading idling or
--- /dev/null
+From 06d5afd4d640eea67f5623e76cd5fc03359b7f3c Mon Sep 17 00:00:00 2001
+From: Daniel Starke <daniel.starke@siemens.com>
+Date: Thu, 14 Apr 2022 02:42:10 -0700
+Subject: tty: n_gsm: fix wrong signal octet encoding in convergence layer type 2
+
+From: Daniel Starke <daniel.starke@siemens.com>
+
+commit 06d5afd4d640eea67f5623e76cd5fc03359b7f3c upstream.
+
+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 5.5.2 describes that the signal octet in
+convergence layer type 2 can be either one or two bytes. The length is
+encoded in the EA bit. This is set 1 for the last byte in the sequence.
+gsmtty_modem_update() handles this correctly but gsm_dlci_data_output()
+fails to set EA to 1. There is no case in which we encode two signal octets
+as there is no case in which we send out a break signal.
+Therefore, always set the EA bit to 1 for the signal octet to fix this.
+
+Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
+Cc: stable@vger.kernel.org
+Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
+Link: https://lore.kernel.org/r/20220414094225.4527-5-daniel.starke@siemens.com
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/tty/n_gsm.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/drivers/tty/n_gsm.c
++++ b/drivers/tty/n_gsm.c
+@@ -839,7 +839,7 @@ static int gsm_dlci_data_output(struct g
+ break;
+ case 2: /* Unstructed with modem bits.
+ Always one byte as we never send inline break data */
+- *dp++ = gsm_encode_modem(dlci);
++ *dp++ = (gsm_encode_modem(dlci) << 1) | EA;
+ break;
+ }
+ WARN_ON(kfifo_out_locked(dlci->fifo, dp , len, &dlci->lock) != len);