USB: serial: kobil_sct: fix modem-status error handling

BugLink: https://bugs.launchpad.net/bugs/1836287
[ 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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/usb/serial/kobil_sct.c b/drivers/usb/serial/kobil_sct.c
index a31ea7e194dd7ab2f9fa022581cc32e2e25aa305..a6ebed1e0f2026256b64d6bd90a52cfe0808b972 100644 (file)
--- 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;
 }