linux-kernel - [PATCH 07/20] tty: n_gsm: fix malformed counter for out of frame data

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Date:   Thu, 14 Apr 2022 02:42:12 -0700
From:   "D. Starke" <daniel.starke@...mens.com>
To:     linux-serial@...r.kernel.org, gregkh@...uxfoundation.org,
        jirislaby@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        Daniel Starke <daniel.starke@...mens.com>
Subject: [PATCH 07/20] tty: n_gsm: fix malformed counter for out of frame data

From: Daniel Starke <daniel.starke@...mens.com>

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@...r.kernel.org
Signed-off-by: Daniel Starke <daniel.starke@...mens.com>
---
 drivers/tty/n_gsm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 4ce18b42c37a..2e3da8a4697e 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -2044,7 +2044,8 @@ static void gsm1_receive(struct gsm_mux *gsm, unsigned char c)
 		}
 		/* 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
-- 
2.25.1