tty: n_gsm: fix malformed counter for out of frame data

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: e1eaea4 ("tty: n_gsm line discipline")
Cc: [email protected]
Signed-off-by: Daniel Starke <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: dstarke-siemens

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