Do not access nextCellIndex (nor Text) past the end

At least for Winfried CppunitTest_sd_import_tests aborts with triggering the
assert in OUString::operator[] at (presumably past-the-end) index 18 from

com::sun::star::i18n::BreakIterator_th::makeIndex (this=0x2b775adf9440,
  Text=..., nStartPos=18) at
  i18npool/source/breakiterator/breakiterator_th.cxx:122
com::sun::star::i18n::BreakIterator_CTL::previousCharacters
  (this=0x2b775adf9440, Text=..., nStartPos=18,
  rLocale=..., nCharacterIteratorMode=1, nCount=1, nDone=@0x7fff9a84a8fc: 0) at
  i18npool/source/breakiterator/breakiterator_ctl.cxx:62
com::sun::star::i18n::BreakIteratorImpl::previousCharacters
  (this=0x2b775ae00a98, Text=..., nStartPos=18, rLocale=...,
  nCharacterIteratorMode=1, nCount=1, nDone=@0x7fff9a84a8fc: 0) at
  i18npool/source/breakiterator/breakiteratorImpl.cxx:65
ServerFontLayout::setNeedFallback (this=0xfba5d0, rArgs=..., nCharPos=17,
  bRightToLeft=false) at vcl/generic/glyphs/gcach_layout.cxx:114
HbLayoutEngine::layout (this=0xfba670, rLayout=..., rArgs=...) at
  vcl/generic/glyphs/gcach_layout.cxx:437
...

and from the preceding if block in BreakIterator_th::makeIndex it indeed looks
like the invariant is that nextCellIndex need not be larger than cellIndexSize
which needs not be larger than Text (ake cachedText) getLength().

Change-Id: Ib92a76020b2bb3902c5e58aa2e6c4e679e51b94a

1 files changed, 2 insertions, 1 deletions

diff --git a/i18npool/source/breakiterator/breakiterator_th.cxx b/i18npool/source/breakiterator/breakiterator_th.cxx
index 2e34af376155..82d7b53665e0 100644
--- a/i18npool/source/breakiterator/breakiterator_th.cxx
+++ b/i18npool/source/breakiterator/breakiterator_th.cxx
@@ -119,7 +119,8 @@ void SAL_CALL BreakIterator_th::makeIndex(const OUString& Text, sal_Int32 nStart
         // reset nextCell for new Text
         memset(nextCellIndex, 0, cellIndexSize * sizeof(sal_Int32));
     }
-    else if (nextCellIndex[nStartPos] > 0 || ! is_Thai(Text[nStartPos]))
+    else if (nStartPos >= Text.getLength() || nextCellIndex[nStartPos] > 0
+             || !is_Thai(Text[nStartPos]))
         return;
 
     const sal_Unicode* str = cachedText.getStr();