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Commit 9d13d3e0 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
Browse files

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



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.

Reported-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Tested-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ee0ea51a

drivers/usb/core/config.c

+4 −2
Original line number Diff line number Diff line
@@ -955,10 +955,12 @@ int usb_get_bos_descriptor(struct usb_device *dev) 
	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) {