[src/trunk]: src/sys/dev/usb Be more defensive towards malicious USB devices

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

details:   https://anonhg.NetBSD.org/src/rev/8308dd8fb19f
branches:  trunk
changeset: 828328:8308dd8fb19f
user:      khorben <khorben%NetBSD.org@localhost>
date:      Fri Dec 08 14:46:18 2017 +0000

description:
Be more defensive towards malicious USB devices

This avoids potential panics due to 0-sized memory allocation attempts,
which could be triggered by malicious USB devices.

Tested on NetBSD/amd64 with a Sony Xperia X (SailfishOS).

Based on an initial patch by Nick Hudson <skrll%NetBSD.org@localhost>, thanks!

Fixes PR kern/52383.

XXX pull-up to netbsd-7, netbsd-8

LGTM xtos@

diffstat:

 sys/dev/usb/usb_subr.c |  18 ++++++++++++++++--
 1 files changed, 16 insertions(+), 2 deletions(-)

diffs (53 lines):

diff -r a22e8e1329ea -r 8308dd8fb19f sys/dev/usb/usb_subr.c
--- a/sys/dev/usb/usb_subr.c    Fri Dec 08 14:40:45 2017 +0000
+++ b/sys/dev/usb/usb_subr.c    Fri Dec 08 14:46:18 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: usb_subr.c,v 1.221 2017/10/28 00:37:12 pgoyette Exp $  */
+/*     $NetBSD: usb_subr.c,v 1.222 2017/12/08 14:46:18 khorben Exp $   */
 /*     $FreeBSD: src/sys/dev/usb/usb_subr.c,v 1.18 1999/11/17 22:33:47 n_hibma Exp $   */
 
 /*
@@ -32,7 +32,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: usb_subr.c,v 1.221 2017/10/28 00:37:12 pgoyette Exp $");
+__KERNEL_RCSID(0, "$NetBSD: usb_subr.c,v 1.222 2017/12/08 14:46:18 khorben Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_compat_netbsd.h"
@@ -609,6 +609,10 @@
                return err;
        }
        len = UGETW(cd.wTotalLength);
+       if (len == 0) {
+               DPRINTF("empty short descriptor", 0, 0, 0, 0);
+               return USBD_INVAL;
+       }
        cdp = kmem_alloc(len, KM_SLEEP);
 
        /* Get the full descriptor.  Try a few times for slow devices. */
@@ -635,6 +639,11 @@
                err = usbd_get_bos_desc(dev, index, &bd);
                if (!err) {
                        int blen = UGETW(bd.wTotalLength);
+                       if (blen == 0) {
+                               DPRINTF("empty bos descriptor", 0, 0, 0, 0);
+                               err = USBD_INVAL;
+                               goto bad;
+                       }
                        bdp = kmem_alloc(blen, KM_SLEEP);
 
                        /* Get the full desc */
@@ -724,6 +733,11 @@
 
        /* Allocate and fill interface data. */
        nifc = cdp->bNumInterface;
+       if (nifc == 0) {
+               DPRINTF("no interfaces", 0, 0, 0, 0);
+               err = USBD_INVAL;
+               goto bad;
+       }
        dev->ud_ifaces = kmem_alloc(nifc * sizeof(struct usbd_interface),
            KM_SLEEP);
        DPRINTFN(5, "dev=%#jx cdesc=%#jx", (uintptr_t)dev, (uintptr_t)cdp,