From aa814edbd31280c5ff3c465c8fdca1ced52dc34d Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Thu, 12 Jan 2017 14:56:11 +0100 Subject: [PATCH] USB: serial: ftdi_sio: fix modem-status error handling commit 427c3a95e3e29e65f59d99aaf320d7506f3eed57 upstream. Make sure to detect short responses when fetching the modem status in order to avoid parsing uninitialised buffer data and having bits of it leak to user space. Note that we still allow for short 1-byte responses. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reviewed-by: Greg Kroah-Hartman Signed-off-by: Johan Hovold Signed-off-by: Willy Tarreau --- drivers/usb/serial/ftdi_sio.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c index 4e865664699b..ba043088582e 100644 --- a/drivers/usb/serial/ftdi_sio.c +++ b/drivers/usb/serial/ftdi_sio.c @@ -2452,8 +2452,12 @@ static int ftdi_get_modem_status(struct usb_serial_port *port, FTDI_SIO_GET_MODEM_STATUS_REQUEST_TYPE, 0, priv->interface, buf, len, WDR_TIMEOUT); - if (ret < 0) { + + /* NOTE: We allow short responses and handle that below. */ + if (ret < 1) { dev_err(&port->dev, "failed to get modem status: %d\n", ret); + if (ret >= 0) + ret = -EIO; ret = usb_translate_errors(ret); goto out; } -- 2.20.1