[src/trunk]: src/sys/sys Avoid undefined operation in signed integer shift in...

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

details:   https://anonhg.NetBSD.org/src/rev/2222cd4af62c
branches:  trunk
changeset: 991245:2222cd4af62c
user:      kamil <kamil%NetBSD.org@localhost>
date:      Wed Jul 04 01:17:32 2018 +0000

description:
Avoid undefined operation in signed integer shift in MAP_ALIGNED()

Cast the shifted byte to unsigned int.

sys/uvm/uvm_mmap.c:914:19, left shift of 255 by 24 places cannot be represented in type 'int'

Detected with Kernel Undefined Behavior Sanitizer.

Reported by <Harry Pantazis>

diffstat:

 sys/sys/mman.h |  4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diffs (18 lines):

diff -r d6fe2d253dcd -r 2222cd4af62c sys/sys/mman.h
--- a/sys/sys/mman.h    Wed Jul 04 00:35:33 2018 +0000
+++ b/sys/sys/mman.h    Wed Jul 04 01:17:32 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: mman.h,v 1.53 2018/01/24 09:04:45 skrll Exp $  */
+/*     $NetBSD: mman.h,v 1.54 2018/07/04 01:17:32 kamil Exp $  */
 
 /*-
  * Copyright (c) 1982, 1986, 1993
@@ -106,7 +106,7 @@
  * Alignment (expressed in log2).  Must be >= log2(PAGE_SIZE) and
  * < # bits in a pointer (32 or 64).
  */
-#define        MAP_ALIGNED(n)          ((n) << MAP_ALIGNMENT_SHIFT)
+#define        MAP_ALIGNED(n)          ((unsigned int)(n) << MAP_ALIGNMENT_SHIFT)
 #define        MAP_ALIGNMENT_SHIFT     24
 #define        MAP_ALIGNMENT_MASK      MAP_ALIGNED(0xff)
 #define        MAP_ALIGNMENT_64KB      MAP_ALIGNED(16) /* 2^16 */