[src/trunk]: src/usr.bin/make make(1): fix undefined behavior in ParseEOF

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

details:   https://anonhg.NetBSD.org/src/rev/5dbdbe8932b6
branches:  trunk
changeset: 978899:5dbdbe8932b6
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sun Dec 06 18:37:04 2020 +0000

description:
make(1): fix undefined behavior in ParseEOF

Adding a number to a null pointer should have been caught by any
Undefined Behavior Sanitizer, but apparently neither GCC nor Clang do
this.

diffstat:

 usr.bin/make/parse.c |  6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diffs (27 lines):

diff -r 59ac523991c8 -r 5dbdbe8932b6 usr.bin/make/parse.c
--- a/usr.bin/make/parse.c      Sun Dec 06 18:13:17 2020 +0000
+++ b/usr.bin/make/parse.c      Sun Dec 06 18:37:04 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: parse.c,v 1.469 2020/12/05 19:46:04 rillig Exp $       */
+/*     $NetBSD: parse.c,v 1.470 2020/12/06 18:37:04 rillig Exp $       */
 
 /*
  * Copyright (c) 1988, 1989, 1990, 1993
@@ -117,7 +117,7 @@
 #include "pathnames.h"
 
 /*     "@(#)parse.c    8.3 (Berkeley) 3/19/94" */
-MAKE_RCSID("$NetBSD: parse.c,v 1.469 2020/12/05 19:46:04 rillig Exp $");
+MAKE_RCSID("$NetBSD: parse.c,v 1.470 2020/12/06 18:37:04 rillig Exp $");
 
 /* types and constants */
 
@@ -2623,7 +2623,7 @@
        ptr = curFile->nextbuf(curFile->nextbuf_arg, &len);
        curFile->buf_ptr = ptr;
        curFile->buf_freeIt = ptr;
-       curFile->buf_end = ptr + len; /* XXX: undefined behavior if ptr == NULL */
+       curFile->buf_end = ptr == NULL ? NULL : ptr + len;
        curFile->lineno = curFile->first_lineno;
        if (ptr != NULL)
                return TRUE;    /* Iterate again */