patch "cdc-acm: fix possible invalid access when processing notification" added to usb-testing

patch "cdc-acm: fix possible invalid access when processing notification" added to usb-testing

[gregkh]

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

    cdc-acm: fix possible invalid access when processing notification

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-testing 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 be merged to the usb-next branch sometime soon,
after it passes testing, and the merge window is open.

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


>From 1bb9914e1730417d530de9ed37e59efdc647146b Mon Sep 17 00:00:00 2001
From: Tobias Herzog <t-herzog@gmx.de>
Date: Thu, 30 Mar 2017 22:15:10 +0200
Subject: cdc-acm: fix possible invalid access when processing notification

Notifications may only be 8 bytes long. Accessing the 9th and
10th byte of unimplemented/unknown notifications may be insecure.
Also check the length of known notifications before accessing anything
behind the 8th byte.

Signed-off-by: Tobias Herzog <t-herzog@gmx.de>
Acked-by: Oliver Neukum <oneukum@suse.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/class/cdc-acm.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 00d55ba8983f..cdabe76960bc 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -323,6 +323,12 @@ static void acm_ctrl_irq(struct urb *urb)
 		break;
 
 	case USB_CDC_NOTIFY_SERIAL_STATE:
+		if (le16_to_cpu(dr->wLength) != 2) {
+			dev_dbg(&acm->control->dev,
+				"%s - malformed serial state\n", __func__);
+			break;
+		}
+
 		newctrl = get_unaligned_le16(data);
 
 		if (!acm->clocal && (acm->ctrlin & ~newctrl & ACM_CTRL_DCD)) {
@@ -359,11 +365,10 @@ static void acm_ctrl_irq(struct urb *urb)
 
 	default:
 		dev_dbg(&acm->control->dev,
-			"%s - unknown notification %d received: index %d "
-			"len %d data0 %d data1 %d\n",
+			"%s - unknown notification %d received: index %d len %d\n",
 			__func__,
-			dr->bNotificationType, dr->wIndex,
-			dr->wLength, data[0], data[1]);
+			dr->bNotificationType, dr->wIndex, dr->wLength);
+
 		break;
 	}
 exit:
-- 
2.12.1