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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Johan Hovold <johan@kernel.org>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.18 020/228] USB: serial: kobil_sct: fix modem-status error handling
Date:   Tue,  2 Oct 2018 06:21:57 -0700
Message-Id: <20181002132500.431463254@linuxfoundation.org>
In-Reply-To: <20181002132459.032960735@linuxfoundation.org>
References: <20181002132459.032960735@linuxfoundation.org>
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4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/serial/kobil_sct.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

--- a/drivers/usb/serial/kobil_sct.c
+++ b/drivers/usb/serial/kobil_sct.c
@@ -393,12 +393,20 @@ static int kobil_tiocmget(struct tty_str
 			  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;
 }