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

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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 <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2017-01-12 14:56:11 +01:00 committed by Greg Kroah-Hartman
parent 4420e0f8fd
commit f3d56f7a58
1 changed files with 5 additions and 1 deletions
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6
drivers/usb/serial/ftdi_sio.c
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@ -2433,8 +2433,12 @@ 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;
}