From 11a785b65bd1758b3ae9734659fd46ebdc1d2680 Mon Sep 17 00:00:00 2001
From: millert <millert@openbsd.org>
Date: Mon, 21 Jul 2008 17:30:08 +0000
Subject: [PATCH] Extra sanity checking for afree();  OK deraadt@ and pvalchev@

---
 bin/ksh/alloc.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/bin/ksh/alloc.c b/bin/ksh/alloc.c
index 8aaf4ff0726..7e41c2cd5be 100644
--- a/bin/ksh/alloc.c
+++ b/bin/ksh/alloc.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: alloc.c,v 1.7 2004/02/19 18:51:17 deraadt Exp $	*/
+/*	$OpenBSD: alloc.c,v 1.8 2008/07/21 17:30:08 millert Exp $	*/
 /*
  * Copyright (c) 2002 Marc Espie.
  *
@@ -102,13 +102,20 @@ aresize(void *ptr, size_t size, Area *ap)
 void
 afree(void *ptr, Area *ap)
 {
-	struct link *l;
+	struct link *l, *l2;
 
 	if (!ptr)
 		return;
 
 	l = P2L(ptr);
 
+	for (l2 = ap->freelist; l2 != NULL; l2 = l2->next) {
+		if (l == l2)
+			break;
+	}
+	if (l2 == NULL)
+		internal_errorf(1, "afree: %p not present in area %p", ptr, ap);
+
 	if (l->prev)
 		l->prev->next = l->next;
 	else
-- 
2.20.1