ooxml spec allow ext ref to non existent entry, fdo#54558

Change-Id: I717917d04a93975472d60248eb61066cd04d1bbe

1 files changed, 7 insertions, 1 deletions

diff --git a/sc/source/filter/oox/extlstcontext.cxx b/sc/source/filter/oox/extlstcontext.cxx
index c1949e8af217..78fd832fc540 100644
--- a/sc/source/filter/oox/extlstcontext.cxx
+++ b/sc/source/filter/oox/extlstcontext.cxx
@@ -200,7 +200,13 @@ ContextHandlerRef ExtGlobalContext::onCreateContext( sal_Int32 nElement, const A
         if(nElement == XLS_EXT_TOKEN( cfRule ))
         {
             rtl::OUString aId = rAttribs.getString( XML_id, rtl::OUString() );
-            void* pInfo = getExtLst().find( aId )->second;
+
+            // an ext entrie does not need to have an existing corresponding entry
+            ExtLst::const_iterator aExt = getExtLst().find( aId );
+            if(aExt == getExtLst().end())
+                return NULL;
+
+            void* pInfo = aExt->second;
             if (!pInfo)
             {
                 return NULL;