From: Oliver Neukum <oneukum@suse.com>
Date: Tue, 15 Mar 2016 09:14:04 +0000 (+0100)
Subject: USB: cdc-acm: more sanity checking
X-Git-Tag: v4.1.12-92~150^2~32
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=d633c09cbbca18ad166f5a160806e69441bc155b;p=users%2Fjedix%2Flinux-maple.git

USB: cdc-acm: more sanity checking

Orabug: 23331129

[ Upstream commit 8835ba4a39cf53f705417b3b3a94eb067673f2c9 ]

An attack has become available which pretends to be a quirky
device circumventing normal sanity checks and crashes the kernel
by an insufficient number of interfaces. This patch adds a check
to the code path for quirky devices.

Signed-off-by: Oliver Neukum <ONeukum@suse.com>
CC: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
(cherry picked from commit a635bc779e7b7748c9b0b773eaf08a7f2184ec50)

Signed-off-by: Dan Duval <dan.duval@oracle.com>
---

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index cd03fe07f1b1..4cb106accd74 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1118,6 +1118,9 @@ static int acm_probe(struct usb_interface *intf,
 	if (quirks == NO_UNION_NORMAL) {
 		data_interface = usb_ifnum_to_if(usb_dev, 1);
 		control_interface = usb_ifnum_to_if(usb_dev, 0);
+		/* we would crash */
+		if (!data_interface || !control_interface)
+			return -ENODEV;
 		goto skip_normal_probe;
 	}