[src/trunk]: src/sys/dev/usb uhidev(9): Define UHIDEV_MAXREPID = 255.

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

details:   https://anonhg.NetBSD.org/src/rev/4d6e10926d8e
branches:  trunk
changeset: 364546:4d6e10926d8e
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Mon Mar 28 12:44:37 2022 +0000

description:
uhidev(9): Define UHIDEV_MAXREPID = 255.

Report ids are limited by the HID spec to a single byte.

- Clamp max report id in report descriptor to this.

- Prune dead refcnt-overflow error branches.  Assert instead.

diffstat:

 sys/dev/usb/uhidev.c |  21 +++++++++------------
 sys/dev/usb/uhidev.h |   3 ++-
 2 files changed, 11 insertions(+), 13 deletions(-)

diffs (74 lines):

diff -r 4b1276e18317 -r 4d6e10926d8e sys/dev/usb/uhidev.c
--- a/sys/dev/usb/uhidev.c      Mon Mar 28 12:44:28 2022 +0000
+++ b/sys/dev/usb/uhidev.c      Mon Mar 28 12:44:37 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uhidev.c,v 1.91 2022/03/28 12:44:28 riastradh Exp $    */
+/*     $NetBSD: uhidev.c,v 1.92 2022/03/28 12:44:37 riastradh Exp $    */
 
 /*
  * Copyright (c) 2001, 2012 The NetBSD Foundation, Inc.
@@ -35,7 +35,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uhidev.c,v 1.91 2022/03/28 12:44:28 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uhidev.c,v 1.92 2022/03/28 12:44:37 riastradh Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_usb.h"
@@ -458,7 +458,7 @@
                if ((int)h.report_ID > maxid)
                        maxid = h.report_ID;
        hid_end_parse(d);
-       return maxid;
+       return MIN(maxid, UHIDEV_MAXREPID);
 }
 
 static int
@@ -671,11 +671,11 @@
 
        /*
         * If the pipes are already open, just increment the reference
-        * count, or fail if it would overflow.
+        * count.  The reference count is limited by the number of
+        * report ids, so this can't overflow.
         */
        if (sc->sc_refcnt) {
-               if (sc->sc_refcnt == INT_MAX)
-                       return EBUSY;
+               KASSERT(sc->sc_refcnt < UHIDEV_MAXREPID);
                sc->sc_refcnt++;
                return 0;
        }
@@ -700,12 +700,9 @@
        if (error)
                goto out;
        if (sc->sc_refcnt) {
-               if (sc->sc_refcnt == INT_MAX) {
-                       error = EBUSY;
-               } else {
-                       sc->sc_refcnt++;
-                       error = 0;
-               }
+               KASSERT(sc->sc_refcnt < UHIDEV_MAXREPID);
+               sc->sc_refcnt++;
+               error = 0;
                goto out0;
        }
        mutex_exit(&sc->sc_lock);
diff -r 4b1276e18317 -r 4d6e10926d8e sys/dev/usb/uhidev.h
--- a/sys/dev/usb/uhidev.h      Mon Mar 28 12:44:28 2022 +0000
+++ b/sys/dev/usb/uhidev.h      Mon Mar 28 12:44:37 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uhidev.h,v 1.26 2022/03/28 12:44:17 riastradh Exp $    */
+/*     $NetBSD: uhidev.h,v 1.27 2022/03/28 12:44:37 riastradh Exp $    */
 
 /*
  * Copyright (c) 2001 The NetBSD Foundation, Inc.
@@ -54,5 +54,6 @@
     usbd_callback, void *);
 
 #define        UHIDEV_OSIZE    64
+#define        UHIDEV_MAXREPID 255
 
 #endif /* _DEV_USB_UHIDEV_H_ */