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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     Johan Hovold <johan@kernel.org>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL 4.18 020/136] USB: serial: kobil_sct: fix modem-status
 error handling
Thread-Topic: [PATCH AUTOSEL 4.18 020/136] USB: serial: kobil_sct: fix
 modem-status error handling
Thread-Index: AQHUTjKTjRXh+F5Bt0G0nJQV8ar/Og==
Date:   Mon, 17 Sep 2018 03:00:23 +0000
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From: Johan Hovold <johan@kernel.org>

[ Upstream commit a420b5d939ee58f1d950f0ea782834056520aeaa ]

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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 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);
=20
-	dev_dbg(&port->dev, "%s - Send get_status_line_state URB returns: %i. Sta=
tusline: %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 >=3D 0)
+			result =3D -EIO;
+		goto out_free;
+	}
+
+	dev_dbg(&port->dev, "Statusline: %02x\n", transfer_buffer[0]);
=20
 	result =3D 0;
 	if ((transfer_buffer[0] & SUSBCR_GSL_DSR) !=3D 0)
 		result =3D TIOCM_DSR;
+out_free:
 	kfree(transfer_buffer);
 	return result;
 }
--=20
2.17.1