Patch "USB: serial: ftdi_sio: fix modem-status error handling" has been added to the 4.4-stable tree

Patch "USB: serial: ftdi_sio: fix modem-status error handling" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

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

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-serial-ftdi_sio-fix-modem-status-error-handling.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 427c3a95e3e29e65f59d99aaf320d7506f3eed57 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Thu, 12 Jan 2017 14:56:11 +0100
Subject: USB: serial: ftdi_sio: fix modem-status error handling

From: Johan Hovold <johan@kernel.org>

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>

---
 drivers/usb/serial/ftdi_sio.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -2433,8 +2433,12 @@ static int ftdi_get_modem_status(struct
 			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;
 	}


Patches currently in stable-queue which might be from johan@kernel.org are

queue-4.4/usb-serial-ftdi_sio-fix-modem-status-error-handling.patch
queue-4.4/usb-serial-cp210x-add-new-ids-for-ge-bx50v3-boards.patch
queue-4.4/usb-serial-ark3116-fix-register-accessor-error-handling.patch
queue-4.4/usb-serial-digi_acceleport-fix-oob-data-sanity-check.patch
queue-4.4/usb-serial-ftdi_sio-fix-line-status-over-reporting.patch
queue-4.4/usb-serial-ftdi_sio-fix-extreme-low-latency-setting.patch
queue-4.4/usb-serial-spcp8x5-fix-modem-status-handling.patch
queue-4.4/usb-serial-opticon-fix-cts-retrieval-at-open.patch
queue-4.4/usb-serial-mos7840-fix-another-null-deref-at-open.patch