USB: serial: mct_u232: fix modem-status error handling

Make sure to detect short control-message transfers so that errors are
logged when reading the modem status at open.

Note that while this also avoids initialising the modem status using
uninitialised heap data, these bits could not leak to user space as they
are currently not used.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
This commit is contained in:
Johan Hovold 2017-01-12 14:56:16 +01:00
parent 750acdd781
commit 36356a669e

View file

@ -322,8 +322,12 @@ static int mct_u232_get_modem_stat(struct usb_serial_port *port,
MCT_U232_GET_REQUEST_TYPE,
0, 0, buf, MCT_U232_GET_MODEM_STAT_SIZE,
WDR_TIMEOUT);
if (rc < 0) {
if (rc < MCT_U232_GET_MODEM_STAT_SIZE) {
dev_err(&port->dev, "Get MODEM STATus failed (error = %d)\n", rc);
if (rc >= 0)
rc = -EIO;
*msr = 0;
} else {
*msr = buf[0];