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

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

details:   https://anonhg.NetBSD.org/src/rev/1f73d1c5a936
branches:  trunk
changeset: 936581:1f73d1c5a936
user:      rillig <rillig%NetBSD.org@localhost>
date:      Fri Jul 31 13:56:19 2020 +0000

description:
make(1): fix undefined behavior when parsing incomplete :t modifier

mod[2] must only ever be accessed if mod[1] != '\0'.

diffstat:

 usr.bin/make/var.c |  10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

diffs (38 lines):

diff -r 5dc7cb668954 -r 1f73d1c5a936 usr.bin/make/var.c
--- a/usr.bin/make/var.c        Fri Jul 31 13:49:25 2020 +0000
+++ b/usr.bin/make/var.c        Fri Jul 31 13:56:19 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: var.c,v 1.362 2020/07/31 13:43:44 rillig Exp $ */
+/*     $NetBSD: var.c,v 1.363 2020/07/31 13:56:19 rillig Exp $ */
 
 /*
  * Copyright (c) 1988, 1989, 1990, 1993
@@ -69,14 +69,14 @@
  */
 
 #ifndef MAKE_NATIVE
-static char rcsid[] = "$NetBSD: var.c,v 1.362 2020/07/31 13:43:44 rillig Exp $";
+static char rcsid[] = "$NetBSD: var.c,v 1.363 2020/07/31 13:56:19 rillig Exp $";
 #else
 #include <sys/cdefs.h>
 #ifndef lint
 #if 0
 static char sccsid[] = "@(#)var.c      8.3 (Berkeley) 3/19/94";
 #else
-__RCSID("$NetBSD: var.c,v 1.362 2020/07/31 13:43:44 rillig Exp $");
+__RCSID("$NetBSD: var.c,v 1.363 2020/07/31 13:56:19 rillig Exp $");
 #endif
 #endif /* not lint */
 #endif
@@ -2585,8 +2585,10 @@
 static ApplyModifierResult
 ApplyModifier_To(const char *mod, ApplyModifiersState *st)
 {
+    assert(mod[0] == 't');
+
     st->next = mod + 1;                /* make sure it is set */
-    if (mod[1] == st->endc || mod[1] == ':')
+    if (mod[1] == st->endc || mod[1] == ':' || mod[1] == '\0')
        return AMR_BAD;         /* Found ":t<endc>" or ":t:". */
 
     if (mod[1] == 's')