USB: serial: ftdi_sio: fix latency-timer error handling

Make sure to detect short responses when reading the latency timer to
avoid using stale buffer data.

Note that no heap data would currently leak through sysfs as
ASYNC_LOW_LATENCY is set by default.

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 14:56:12 +01:00
parent 427c3a95e3
commit e3e574ad85

View file

@ -1439,10 +1439,13 @@ static int read_latency_timer(struct usb_serial_port *port)
FTDI_SIO_GET_LATENCY_TIMER_REQUEST_TYPE,
0, priv->interface,
buf, 1, WDR_TIMEOUT);
if (rv < 0)
if (rv < 1) {
dev_err(&port->dev, "Unable to read latency timer: %i\n", rv);
else
if (rv >= 0)
rv = -EIO;
} else {
priv->latency = buf[0];
}
kfree(buf);