[src/trunk]: src/sys/kern Avoid undefined behavior in mq_send1()

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

details:   https://anonhg.NetBSD.org/src/rev/5d116b2d271e
branches:  trunk
changeset: 833641:5d116b2d271e
user:      kamil <kamil%NetBSD.org@localhost>
date:      Wed Jul 04 17:50:18 2018 +0000

description:
Avoid undefined behavior in mq_send1()

Do not shift a signed integer causing change of the signed bit.

sys/kern/sys_mqueue.c:881:23, left shift of 1 by 31 places cannot be represented in type 'int'

Detected with Kernel Undefined Behavior Sanitizer.

Reported by <Harry Pantazis>

diffstat:

 sys/kern/sys_mqueue.c |  6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diffs (27 lines):

diff -r 2291bb33e406 -r 5d116b2d271e sys/kern/sys_mqueue.c
--- a/sys/kern/sys_mqueue.c     Wed Jul 04 17:39:12 2018 +0000
+++ b/sys/kern/sys_mqueue.c     Wed Jul 04 17:50:18 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sys_mqueue.c,v 1.41 2018/07/04 17:39:12 kamil Exp $    */
+/*     $NetBSD: sys_mqueue.c,v 1.42 2018/07/04 17:50:18 kamil Exp $    */
 
 /*
  * Copyright (c) 2007-2011 Mindaugas Rasiukevicius <rmind at NetBSD org>
@@ -43,7 +43,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sys_mqueue.c,v 1.41 2018/07/04 17:39:12 kamil Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sys_mqueue.c,v 1.42 2018/07/04 17:50:18 kamil Exp $");
 
 #include <sys/param.h>
 #include <sys/types.h>
@@ -878,7 +878,7 @@
 
                KASSERT(idx != MQ_PQRESQ);
                TAILQ_INSERT_TAIL(&mq->mq_head[idx], msg, msg_queue);
-               mq->mq_bitmap |= (1 << --idx);
+               mq->mq_bitmap |= (1U << --idx);
        } else {
                mqueue_linear_insert(mq, msg);
        }