[src/trunk]: src/sys/ufs/ffs Avoid unportable shift base -1 in ffs_subr.c

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

details:   https://anonhg.NetBSD.org/src/rev/e9c5357d27d7
branches:  trunk
changeset: 451577:e9c5357d27d7
user:      kamil <kamil%NetBSD.org@localhost>
date:      Tue May 28 03:53:28 2019 +0000

description:
Avoid unportable shift base -1 in ffs_subr.c

Cast the start variable before the modulo opration to unsigned int.

Detected with kUBSan.

diffstat:

 sys/ufs/ffs/ffs_subr.c |  8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diffs (36 lines):

diff -r 90ca84be94fd -r e9c5357d27d7 sys/ufs/ffs/ffs_subr.c
--- a/sys/ufs/ffs/ffs_subr.c    Tue May 28 03:52:08 2019 +0000
+++ b/sys/ufs/ffs/ffs_subr.c    Tue May 28 03:53:28 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ffs_subr.c,v 1.50 2018/07/04 02:02:15 kamil Exp $      */
+/*     $NetBSD: ffs_subr.c,v 1.51 2019/05/28 03:53:28 kamil Exp $      */
 
 /*
  * Copyright (c) 1982, 1986, 1989, 1993
@@ -36,7 +36,7 @@
 #endif
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ffs_subr.c,v 1.50 2018/07/04 02:02:15 kamil Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ffs_subr.c,v 1.51 2019/05/28 03:53:28 kamil Exp $");
 
 #include <sys/param.h>
 
@@ -313,7 +313,7 @@
                end = ufs_rw32(cgp->cg_nclusterblks, needswap);
        mapp = &freemapp[start / NBBY];
        map = *mapp++;
-       bit = 1U << (start % NBBY);
+       bit = 1U << ((unsigned int)start % NBBY);
        for (i = start; i < end; i++) {
                if ((map & bit) == 0)
                        break;
@@ -334,7 +334,7 @@
                end = -1;
        mapp = &freemapp[start / NBBY];
        map = *mapp--;
-       bit = 1U << (start % NBBY);
+       bit = 1U << ((unsigned int)start % NBBY);
        for (i = start; i > end; i--) {
                if ((map & bit) == 0)
                        break;