Patch "USB: core: prevent malicious bNumInterfaces overflow" has been added to the 3.18-stable tree

[<gregkh@linuxfoundation.org>]

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

    USB: core: prevent malicious bNumInterfaces overflow

to the 3.18-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-core-prevent-malicious-bnuminterfaces-overflow.patch
and it can be found in the queue-3.18 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 48a4ff1c7bb5a32d2e396b03132d20d552c0eca7 Mon Sep 17 00:00:00 2001
From: Alan Stern <stern@rowland.harvard.edu>
Date: Tue, 12 Dec 2017 14:25:13 -0500
Subject: USB: core: prevent malicious bNumInterfaces overflow

From: Alan Stern <stern@rowland.harvard.edu>

commit 48a4ff1c7bb5a32d2e396b03132d20d552c0eca7 upstream.

A malicious USB device with crafted descriptors can cause the kernel
to access unallocated memory by setting the bNumInterfaces value too
high in a configuration descriptor.  Although the value is adjusted
during parsing, this adjustment is skipped in one of the error return
paths.

This patch prevents the problem by setting bNumInterfaces to 0
initially.  The existing code already sets it to the proper value
after parsing is complete.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/core/config.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/usb/core/config.c
+++ b/drivers/usb/core/config.c
@@ -450,6 +450,9 @@ static int usb_parse_configuration(struc
 	unsigned iad_num = 0;
 
 	memcpy(&config->desc, buffer, USB_DT_CONFIG_SIZE);
+	nintf = nintf_orig = config->desc.bNumInterfaces;
+	config->desc.bNumInterfaces = 0;	// Adjusted later
+
 	if (config->desc.bDescriptorType != USB_DT_CONFIG ||
 	    config->desc.bLength < USB_DT_CONFIG_SIZE ||
 	    config->desc.bLength > size) {
@@ -463,7 +466,6 @@ static int usb_parse_configuration(struc
 	buffer += config->desc.bLength;
 	size -= config->desc.bLength;
 
-	nintf = nintf_orig = config->desc.bNumInterfaces;
 	if (nintf > USB_MAXINTERFACES) {
 		dev_warn(ddev, "config %d has too many interfaces: %d, "
 		    "using maximum allowed: %d\n",


Patches currently in stable-queue which might be from stern@rowland.harvard.edu are

queue-3.18/usb-core-prevent-malicious-bnuminterfaces-overflow.patch
queue-3.18/usb-uas-and-storage-add-us_fl_broken_fua-for-another-jmicron-jms567-id.patch