Patch "USB: core: fix out-of-bounds access bug in usb_get_bos_descriptor()" has been added to the 4.13-stable tree

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

USB: core: fix out-of-bounds access bug in usb_get_bos_descriptor()

to the 4.13-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-fix-out-of-bounds-access-bug-in-usb_get_bos_descriptor.patch
and it can be found in the queue-4.13 subdirectory.

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

From: Alan Stern <[email protected]>
Date: Wed, 18 Oct 2017 12:49:38 -0400
Subject: USB: core: fix out-of-bounds access bug in usb_get_bos_descriptor()

From: Alan Stern <[email protected]>

commit 1c0edc3633b56000e18d82fc241e3995ca18a69e upstream.

Andrey used the syzkaller fuzzer to find an out-of-bounds memory access in usb_get_bos_descriptor(). The code wasn't checking that the next usb_dev_cap_header structure could fit into the remaining buffer space.

This patch fixes the error and also reduces the bNumDeviceCaps field in the header to match the actual number of capabilities found, in cases where there are fewer than expected.

---
 drivers/usb/core/config.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

@@ -960,10 +960,12 @@ int usb_get_bos_descriptor(struct usb_de
 	for (i = 0; i < num; i++) {
 		buffer += length;
 		cap = (struct usb_dev_cap_header *)buffer;
-		length = cap->bLength;
 
-		if (total_len < length)
+		if (total_len < sizeof(*cap) || total_len < cap->bLength) {
+			dev->bos->desc->bNumDeviceCaps = i;
 			break;
+		}
+		length = cap->bLength;
 		total_len -= length;
 
 		if (cap->bDescriptorType != USB_DT_DEVICE_CAPABILITY) {

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

queue-4.13/usb-devio-revert-usb-devio-don-t-corrupt-user-memory.patch queue-4.13/usb-hub-allow-reset-retry-for-usb2-devices-on-connect-bounce.patch queue-4.13/usb-core-fix-out-of-bounds-access-bug-in-usb_get_bos_descriptor.patch queue-4.13/usb-quirks-add-quirk-for-worlde-mini-midi-keyboard.patch