From: Johan Hovold <johan@xxxxxxxxxx> 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit 5ed8d41023751bdd3546f2fe4118304357efe8d2 upstream. Make sure to detect short control transfers and return zero on success when retrieving the modem status. This fixes the TIOCMGET implementation which since e1ed212d8593 ("USB: spcp8x5: add proper modem-status support") has returned TIOCM_LE on successful retrieval, and avoids leaking bits from the stack on short transfers. This also fixes the carrier-detect implementation which since the above mentioned commit unconditionally has returned true. Fixes: e1ed212d8593 ("USB: spcp8x5: add proper modem-status support") Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Johan Hovold <johan@xxxxxxxxxx> Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> --- drivers/usb/serial/spcp8x5.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/usb/serial/spcp8x5.c b/drivers/usb/serial/spcp8x5.c index ab754d23244c..5fe33cc6a8e3 100644 --- a/drivers/usb/serial/spcp8x5.c +++ b/drivers/usb/serial/spcp8x5.c @@ -233,11 +233,17 @@ static int spcp8x5_get_msr(struct usb_serial_port *port, u8 *status) ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), GET_UART_STATUS, GET_UART_STATUS_TYPE, 0, GET_UART_STATUS_MSR, buf, 1, 100); - if (ret < 0) + if (ret < 1) { dev_err(&port->dev, "failed to get modem status: %d", ret); + if (ret >= 0) + ret = -EIO; + goto out; + } dev_dbg(&port->dev, "0xc0:0x22:0:6 %d - 0x02%x", ret, *buf); *status = *buf; + ret = 0; +out: kfree(buf); return ret; -- 2.12.0