Do not calculate a pointer to a memory location before the beginning of

a static array.  Christos Zoulas, Robert Elz, and Andreas Gustafsson
point out that is undefined behaviour by the C standard even if we
never access the pointer.

diff --git a/usr.bin/mandoc/man_validate.c b/usr.bin/mandoc/man_validate.c
index 4c303d8..d35048d 100644 (file)
--- a/usr.bin/mandoc/man_validate.c
+++ b/usr.bin/mandoc/man_validate.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: man_validate.c,v 1.105 2018/04/11 17:10:35 schwarze Exp $ */
+/*     $OpenBSD: man_validate.c,v 1.106 2018/08/16 15:04:45 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010, 2012-2018 Ingo Schwarze <schwarze@openbsd.org>
@@ -52,7 +52,7 @@ static        void      post_UR(CHKARGS);
 static void      post_in(CHKARGS);
 static void      post_vs(CHKARGS);
 
-static const v_check __man_valids[MAN_MAX - MAN_TH] = {
+static const v_check man_valids[MAN_MAX - MAN_TH] = {
        post_TH,    /* TH */
        NULL,       /* SH */
        NULL,       /* SS */
@@ -90,7 +90,6 @@ static        const v_check __man_valids[MAN_MAX - MAN_TH] = {
        post_UR,    /* MT */
        NULL,       /* ME */
 };
-static const v_check *man_valids = __man_valids - MAN_TH;
 
 
 void
@@ -136,7 +135,7 @@ man_node_validate(struct roff_man *man)
                        break;
                }
                assert(n->tok >= MAN_TH && n->tok < MAN_MAX);
-               cp = man_valids + n->tok;
+               cp = man_valids + (n->tok - MAN_TH);
                if (*cp)
                        (*cp)(man, n);
                if (man->last == n)

diff --git a/usr.bin/mandoc/mdoc_validate.c b/usr.bin/mandoc/mdoc_validate.c
index cbc6282..03a5c03 100644 (file)
--- a/usr.bin/mandoc/mdoc_validate.c
+++ b/usr.bin/mandoc/mdoc_validate.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: mdoc_validate.c,v 1.275 2018/08/01 16:00:54 schwarze Exp $ */
+/*     $OpenBSD: mdoc_validate.c,v 1.276 2018/08/16 15:04:45 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2018 Ingo Schwarze <schwarze@openbsd.org>
@@ -114,7 +114,7 @@ static      void     post_useless(POST_ARGS);
 static void     post_xr(POST_ARGS);
 static void     post_xx(POST_ARGS);
 
-static const v_post __mdoc_valids[MDOC_MAX - MDOC_Dd] = {
+static const v_post mdoc_valids[MDOC_MAX - MDOC_Dd] = {
        post_dd,        /* Dd */
        post_dt,        /* Dt */
        post_os,        /* Os */
@@ -236,7 +236,6 @@ static      const v_post __mdoc_valids[MDOC_MAX - MDOC_Dd] = {
        NULL,           /* %U */
        NULL,           /* Ta */
 };
-static const v_post *const mdoc_valids = __mdoc_valids - MDOC_Dd;
 
 #define        RSORD_MAX 14 /* Number of `Rs' blocks. */
 
@@ -355,7 +354,7 @@ mdoc_node_validate(struct roff_man *mdoc)
                }
 
                assert(n->tok >= MDOC_Dd && n->tok < MDOC_MAX);
-               p = mdoc_valids + n->tok;
+               p = mdoc_valids + (n->tok - MDOC_Dd);
                if (*p)
                        (*p)(mdoc);
                if (mdoc->last == n)