From cd936621379d513bd768319219840b003a45e729 Mon Sep 17 00:00:00 2001

From: Zhenguo Zhao <Zhenguo.Zhao1@unisoc.com>

Date: Fri, 20 Aug 2021 20:17:46 +0800

Subject: [PATCH] tty: n_gsm: Modify cr bit value when config requester

Git-commit: cd936621379d513bd768319219840b003a45e729

Patch-mainline: v5.16-rc1

References: git-fixes

When n_gsm config "initiator=0",as requester,gsmld will receive dlci

SABM and DISC control command frame,the CR bit value should be 1.

If cr == 0,it will goto invalid,and it can't send UA response

frame and open requster dlci.

        case SABM|PF:

-               if (cr == 0)

+               if (cr == 0) {

+                       printk("gsm_queue invalid\n");

                        goto invalid;

+                       }

Example,gsmld receive dlc0 SABM command frame:f9 03 3f 01 1c f9

but gsmld goto invalid.

Kernel test log:

[  101.794705] c0 gsmld_receive: 00000000: f9 03 3f 01 1c f9

[  101.803341] c0 <-- 0) C: SABM(P)

[  101.811371] c0 gsm_queue invalid

Signed-off-by: Zhenguo Zhao <Zhenguo.Zhao1@unisoc.com>

Link: https://lore.kernel.org/r/1629461872-26965-2-git-send-email-zhenguo6858@gmail.com

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Acked-by: Takashi Iwai <tiwai@suse.de>

---

 drivers/tty/n_gsm.c |    4 ++--

 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/tty/n_gsm.c

+++ b/drivers/tty/n_gsm.c

@@ -1779,7 +1779,7 @@ static void gsm_queue(struct gsm_mux *gs

 	switch (gsm->control) {

 	case SABM|PF:

-		if (cr == 0)

+		if (cr == 1)

 			goto invalid;

 		if (dlci == NULL)

 			dlci = gsm_dlci_alloc(gsm, address);

@@ -1793,7 +1793,7 @@ static void gsm_queue(struct gsm_mux *gs

 		}

 		break;

 	case DISC|PF:

-		if (cr == 0)

+		if (cr == 1)

 			goto invalid;

 		if (dlci == NULL || dlci->state == DLCI_CLOSED) {

 			gsm_response(gsm, address, DM);