[src/trunk]: src/sys/dev/hid Fix small read overflows when parsing HID tables...

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

details:   https://anonhg.NetBSD.org/src/rev/65206838de11
branches:  trunk
changeset: 968034:65206838de11
user:      maxv <maxv%NetBSD.org@localhost>
date:      Wed Jan 01 09:40:17 2020 +0000

description:
Fix small read overflows when parsing HID tables. Noticed by kASan the
other day while I was playing with vHCI.

diffstat:

 sys/dev/hid/hid.c |  24 +++++++++++++++---------
 1 files changed, 15 insertions(+), 9 deletions(-)

diffs (59 lines):

diff -r f88fc0addd9a -r 65206838de11 sys/dev/hid/hid.c
--- a/sys/dev/hid/hid.c Wed Jan 01 09:35:50 2020 +0000
+++ b/sys/dev/hid/hid.c Wed Jan 01 09:40:17 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: hid.c,v 1.3 2018/11/15 23:01:45 jakllsch Exp $ */
+/*     $NetBSD: hid.c,v 1.4 2020/01/01 09:40:17 maxv Exp $     */
 /*     $FreeBSD: src/sys/dev/usb/hid.c,v 1.11 1999/11/17 22:33:39 n_hibma Exp $ */
 
 /*
@@ -32,7 +32,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: hid.c,v 1.3 2018/11/15 23:01:45 jakllsch Exp $");
+__KERNEL_RCSID(0, "$NetBSD: hid.c,v 1.4 2020/01/01 09:40:17 maxv Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_usb.h"
@@ -149,27 +149,33 @@
        }
        for (;;) {
                p = s->p;
-               if (p >= s->end)
+
+               if (p + 1 > s->end)
                        return 0;
+               bSize = *p++;
 
-               bSize = *p++;
                if (bSize == 0xfe) {
                        /* long item */
+                       if (p + 3 > s->end)
+                               return 0;
                        bSize = *p++;
                        bSize |= *p++ << 8;
                        bTag = *p++;
-                       data = p;
-                       p += bSize;
                        bType = 0xff; /* XXX what should it be */
                } else {
                        /* short item */
                        bTag = bSize >> 4;
                        bType = (bSize >> 2) & 3;
                        bSize &= 3;
-                       if (bSize == 3) bSize = 4;
-                       data = p;
-                       p += bSize;
+                       if (bSize == 3)
+                               bSize = 4;
                }
+
+               data = p;
+               if (p + bSize > s->end)
+                       return 0;
+               p += bSize;
+
                s->p = p;
                switch(bSize) {
                case 0: