From 6da5df470099fc55f20b03ef364af730e7be4ffe Mon Sep 17 00:00:00 2001 From: Hans Petter Selasky Date: Tue, 15 Dec 2020 11:51:17 +0000 Subject: [PATCH] Improve handling of alternate settings in the USB stack. Limit the number of alternate settings to 256. Else the alternate index variable may wrap around. PR: 251856 MFC after: 1 week Submitted by: Ma, Horse Sponsored by: Mellanox Technologies // NVIDIA Networking --- sys/dev/usb/usb_parse.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/sys/dev/usb/usb_parse.c b/sys/dev/usb/usb_parse.c index 5cace00fadc..15bd1c96704 100644 --- a/sys/dev/usb/usb_parse.c +++ b/sys/dev/usb/usb_parse.c @@ -2,7 +2,7 @@ /*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * - * Copyright (c) 2008 Hans Petter Selasky. All rights reserved. + * Copyright (c) 2008-2020 Hans Petter Selasky. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions @@ -141,8 +141,20 @@ usb_idesc_foreach(struct usb_config_descriptor *cd, break; if ((id->bDescriptorType == UDESC_INTERFACE) && (id->bLength >= sizeof(*id))) { - if (ps->iface_no_last == id->bInterfaceNumber) + if (ps->iface_no_last == id->bInterfaceNumber) { + /* + * Don't allow more than 256 alternate + * settings to avoid overflowing the + * alternate index which is a 8-bit + * variable. + */ + if (ps->iface_index_alt == 255) { + DPRINTF("Interface(%u) has more than 256 alternate settings\n", + id->bInterfaceNumber); + continue; + } new_iface = 0; + } ps->iface_no_last = id->bInterfaceNumber; break; }