From a420b5d939ee58f1d950f0ea782834056520aeaa Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Wed, 4 Jul 2018 17:02:18 +0200
Subject: [PATCH] USB: serial: kobil_sct: fix modem-status error handling
Git-commit: a420b5d939ee58f1d950f0ea782834056520aeaa
Patch-mainline: v4.19-rc1
References: bsc#1051510

Make sure to return -EIO in case of a short modem-status read request.

While at it, split the debug message to not include the (zeroed)
transfer-buffer content in case of errors.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/usb/serial/kobil_sct.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/serial/kobil_sct.c b/drivers/usb/serial/kobil_sct.c
index a31ea7e194dd..a6ebed1e0f20 100644
--- a/drivers/usb/serial/kobil_sct.c
+++ b/drivers/usb/serial/kobil_sct.c
@@ -393,12 +393,20 @@ static int kobil_tiocmget(struct tty_struct *tty)
 			  transfer_buffer_length,
 			  KOBIL_TIMEOUT);
 
-	dev_dbg(&port->dev, "%s - Send get_status_line_state URB returns: %i. Statusline: %02x\n",
-		__func__, result, transfer_buffer[0]);
+	dev_dbg(&port->dev, "Send get_status_line_state URB returns: %i\n",
+			result);
+	if (result < 1) {
+		if (result >= 0)
+			result = -EIO;
+		goto out_free;
+	}
+
+	dev_dbg(&port->dev, "Statusline: %02x\n", transfer_buffer[0]);
 
 	result = 0;
 	if ((transfer_buffer[0] & SUSBCR_GSL_DSR) != 0)
 		result = TIOCM_DSR;
+out_free:
 	kfree(transfer_buffer);
 	return result;
 }
-- 
2.18.0