From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Johan Hovold Subject: [PATCH 4.4 36/60] USB: serial: mct_u232: fix modem-status error handling Date: Thu, 11 May 2017 16:12:59 +0200 Message-Id: <20170511141238.633939075@linuxfoundation.org> In-Reply-To: <20170511141237.094835992@linuxfoundation.org> References: <20170511141237.094835992@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Johan Hovold commit 36356a669eddb32917fc4b5c2b9b8bf80ede69de upstream. 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: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reviewed-by: Greg Kroah-Hartman Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman --- drivers/usb/serial/mct_u232.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/drivers/usb/serial/mct_u232.c +++ b/drivers/usb/serial/mct_u232.c @@ -322,8 +322,12 @@ static int mct_u232_get_modem_stat(struc 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];