Patch "cdc-acm: fix possible invalid access when processing notification" has been added to the 4.9-stable tree

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 the 4.9-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:
cdc-acm-fix-possible-invalid-access-when-processing-notification.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Tobias Herzog <[email protected]>
Date: Thu, 30 Mar 2017 22:15:10 +0200
Subject: cdc-acm: fix possible invalid access when processing notification

From: Tobias Herzog <[email protected]>

commit 1bb9914e1730417d530de9ed37e59efdc647146b upstream.

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.

---
 drivers/usb/class/cdc-acm.c |   13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

@@ -311,6 +311,12 @@ 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)) {

@@ -347,11 +353,10 @@ 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:

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/cdc-acm-fix-possible-invalid-access-when-processing-notification.patch