[src/trunk]: src/sys/dev/usb Add missing length checks on descriptors, to pre...

[maxv <maxv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/18dbfaf498af
branches:  trunk
changeset: 459532:18dbfaf498af
user:      maxv <maxv%NetBSD.org@localhost>
date:      Sun Sep 15 09:21:36 2019 +0000

description:
Add missing length checks on descriptors, to prevent buffer overflows.
Found via KASAN+vHCI. Some remain however, but it looks like the code
needs to be re-thought along the way, so it will be fixed later.

diffstat:

 sys/dev/usb/uvideo.c |  25 ++++++++++++++++++++++---
 1 files changed, 22 insertions(+), 3 deletions(-)

diffs (86 lines):

diff -r df848ed45986 -r 18dbfaf498af sys/dev/usb/uvideo.c
--- a/sys/dev/usb/uvideo.c      Sun Sep 15 09:18:17 2019 +0000
+++ b/sys/dev/usb/uvideo.c      Sun Sep 15 09:21:36 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uvideo.c,v 1.47 2019/05/05 03:17:54 mrg Exp $  */
+/*     $NetBSD: uvideo.c,v 1.48 2019/09/15 09:21:36 maxv Exp $ */
 
 /*
  * Copyright (c) 2008 Patrick Mahoney
@@ -42,7 +42,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvideo.c,v 1.47 2019/05/05 03:17:54 mrg Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvideo.c,v 1.48 2019/09/15 09:21:36 maxv Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_usb.h"
@@ -527,6 +527,12 @@
             (ifdesc = usb_desc_iter_next_interface(&iter)) != NULL;
             ++ifaceidx)
        {
+               if (ifdesc->bLength < USB_INTERFACE_DESCRIPTOR_SIZE) {
+                       DPRINTFN(50, ("uvideo_attach: "
+                                     "ignoring incorrect descriptor len=%d\n",
+                                     ifdesc->bLength));
+                       continue;
+               }
                if (ifdesc->bInterfaceClass != UICLASS_VIDEO) {
                        DPRINTFN(50, ("uvideo_attach: "
                                      "ignoring non-uvc interface: "
@@ -884,13 +890,17 @@
 
        switch (desc->bDescriptorSubtype) {
        case UDESC_INPUT_TERMINAL:
+               if (desc->bLength < sizeof(*input))
+                       return USBD_INVAL;
                input = (const uvideo_input_terminal_descriptor_t *)desc;
                switch (UGETW(input->wTerminalType)) {
                case UVIDEO_ITT_CAMERA:
+                       if (desc->bLength < sizeof(*camera))
+                               return USBD_INVAL;
                        camera =
                            (const uvideo_camera_terminal_descriptor_t *)desc;
+
                        ct = &vu->u.vu_camera;
-
                        ct->ct_objective_focal_min =
                            UGETW(camera->wObjectiveFocalLengthMin);
                        ct->ct_objective_focal_max =
@@ -911,12 +921,16 @@
        case UDESC_OUTPUT_TERMINAL:
                break;
        case UDESC_SELECTOR_UNIT:
+               if (desc->bLength < sizeof(*selector))
+                       return USBD_INVAL;
                selector = (const uvideo_selector_unit_descriptor_t *)desc;
 
                uvideo_unit_alloc_sources(vu, selector->bNrInPins,
                                          selector->baSourceID);
                break;
        case UDESC_PROCESSING_UNIT:
+               if (desc->bLength < sizeof(*processing))
+                       return USBD_INVAL;
                processing = (const uvideo_processing_unit_descriptor_t *)desc;
                pu = &vu->u.vu_processing;
 
@@ -928,6 +942,8 @@
                                           processing->bmControls);
                break;
        case UDESC_EXTENSION_UNIT:
+               if (desc->bLength < sizeof(*extension))
+                       return USBD_INVAL;
                extension = (const uvideo_extension_unit_descriptor_t *)desc;
                /* TODO: copy guid */
 
@@ -1081,6 +1097,9 @@
  * interface descriptor, modifying the iterator.  This may be called
  * multiple times because there may be several alternate interfaces
  * associated with the same interface number. */
+/*
+ * XXX XXX XXX: This function accesses descriptors in an unsafe manner.
+ */
 static usbd_status
 uvideo_stream_init_desc(struct uvideo_stream *vs,
                        const usb_interface_descriptor_t *ifdesc,