From 1666ae35d8a1d7fd4183adbcca775f541b8596eb Mon Sep 17 00:00:00 2001
From: dgp <dgp@users.sourceforge.net>
Date: Thu, 31 Jul 2014 19:58:53 +0000
Subject: [a84a720966] Protect against double free in TclOO classChainCache
 teardown.

---
 generic/tclOOCall.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/generic/tclOOCall.c b/generic/tclOOCall.c
index 26fd09f..897f635 100644
--- a/generic/tclOOCall.c
+++ b/generic/tclOOCall.c
@@ -150,7 +150,7 @@ void
 TclOODeleteChain(
     CallChain *callPtr)
 {
-    if (--callPtr->refCount >= 1) {
+    if (callPtr == NULL || --callPtr->refCount >= 1) {
 	return;
     }
     if (callPtr->chain != callPtr->staticChain) {
-- 
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