patch "USB: serial: safe_serial: fix information leak in completion handler" added to usb-linus

patch "USB: serial: safe_serial: fix information leak in completion handler" added to usb-linus

[gregkh]

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

    USB: serial: safe_serial: fix information leak in completion handler

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 8c76d7cd520ebffc1ea9ea0850d87a224a50c7f2 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Mon, 6 Mar 2017 17:36:41 +0100
Subject: USB: serial: safe_serial: fix information leak in completion handler

Add missing sanity check to the bulk-in completion handler to avoid an
integer underflow that could be triggered by a malicious device.

This avoids leaking up to 56 bytes from after the URB transfer buffer to
user space.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/safe_serial.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/usb/serial/safe_serial.c b/drivers/usb/serial/safe_serial.c
index 93c6c9b08daa..8a069aa154ed 100644
--- a/drivers/usb/serial/safe_serial.c
+++ b/drivers/usb/serial/safe_serial.c
@@ -200,6 +200,11 @@ static void safe_process_read_urb(struct urb *urb)
 	if (!safe)
 		goto out;
 
+	if (length < 2) {
+		dev_err(&port->dev, "malformed packet\n");
+		return;
+	}
+
 	fcs = fcs_compute10(data, length, CRC10_INITFCS);
 	if (fcs) {
 		dev_err(&port->dev, "%s - bad CRC %x\n", __func__, fcs);
-- 
2.12.0