From d6ddd89053299a564c683154cdc0d75874162ea0 Mon Sep 17 00:00:00 2001
From: hyenias <58673227+hyenias@users.noreply.github.com>
Date: Mon, 12 Apr 2021 22:15:34 -0400
Subject: [PATCH] Correct memory fault when removing default nameref
 KSH_VERSION (#271)

This commit fixes a segmentation fault when an attempt was made to
unset the default KSH_VERSION variable prior any other nameref
activity such as creating another nameref or even reassigning the
nameref KSH_VERSION to something else.

(new shell without prior nameref activity)
$ nameref
KSH_VERSION=.sh.version
$ unset -n KSH_VERSION
Memory fault

src/cmd/ksh93/sh/name.c: _nv_unset():
- Add a 'Refdict' check before attempting to remove a value from it
  as apparently one does not exist until some sort of nameref
  activity occurs after shell startup as the default nameref of
  'KSH_VERSION=.sh.version' does not create one.
---
 NEWS                            | 6 ++++++
 src/cmd/ksh93/include/version.h | 2 +-
 src/cmd/ksh93/sh/name.c         | 2 +-
 src/cmd/ksh93/tests/nameref.sh  | 3 +++
 4 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/NEWS b/NEWS
index e255bbcbd..3c39c636d 100644
--- a/NEWS
+++ b/NEWS
@@ -3,6 +3,12 @@ For full details, see the git log at: https://github.com/ksh93/ksh
 
 Any uppercase BUG_* names are modernish shell bug IDs.
 
+2021-04-12:
+
+- Corrected a memory fault when an attempt was made to unset the default
+  nameref KSH_VERSION from the shell environment prior to any other name
+  reference variable creation or modificaton.
+
 2021-04-11:
 
 - Fixed two related regressions introduced on 2020-06-16:
diff --git a/src/cmd/ksh93/include/version.h b/src/cmd/ksh93/include/version.h
index 98b87ce21..7e1cf57e2 100644
--- a/src/cmd/ksh93/include/version.h
+++ b/src/cmd/ksh93/include/version.h
@@ -20,7 +20,7 @@
 
 #define SH_RELEASE_FORK	"93u+m"		/* only change if you develop a new ksh93 fork */
 #define SH_RELEASE_SVER	"1.0.0-alpha"	/* semantic version number: https://semver.org */
-#define SH_RELEASE_DATE	"2021-04-11"	/* must be in this format for $((.sh.version)) */
+#define SH_RELEASE_DATE	"2021-04-12"	/* must be in this format for $((.sh.version)) */
 #define SH_RELEASE_CPYR	"(c) 2020-2021 Contributors to ksh " SH_RELEASE_FORK
 
 /* Scripts sometimes field-split ${.sh.version}, so don't change amount of whitespace. */
diff --git a/src/cmd/ksh93/sh/name.c b/src/cmd/ksh93/sh/name.c
index 01a969016..b77e82ff3 100644
--- a/src/cmd/ksh93/sh/name.c
+++ b/src/cmd/ksh93/sh/name.c
@@ -2578,7 +2578,7 @@ void	_nv_unset(register Namval_t *np,int flags)
 	else if(nv_isref(np) && !nv_isattr(np,NV_EXPORT|NV_MINIMAL) && np->nvalue.nrp)
 	{
 
-		if(np->nvalue.nrp->root)
+		if(np->nvalue.nrp->root && Refdict)
 			dtdelete(Refdict,(void*)np->nvalue.nrp);
 		if(np->nvalue.nrp->sub)
 			free(np->nvalue.nrp->sub);
diff --git a/src/cmd/ksh93/tests/nameref.sh b/src/cmd/ksh93/tests/nameref.sh
index c911f39cd..5ed56a00e 100755
--- a/src/cmd/ksh93/tests/nameref.sh
+++ b/src/cmd/ksh93/tests/nameref.sh
@@ -684,4 +684,7 @@ typeset -n ref='arr[2]'
 
 $SHELL  2> /dev/null -c 'function x { nameref lv=gg ; compound -A lv.c=( [4]=( x=1 )) ; } ; compound gg ; x' || err_exit 'compound array assignment with nameref in a function failed'
 
+$SHELL -c 'unset -n KSH_VERSION' 2> /dev/null || err_exit 'Unable to unset nameref KSH_VERSION.'
+
+# ======
 exit $((Errors<125?Errors:125))