1 files changed, 2 insertions, 0 deletions
diff --git a/vcl/source/filter/igif/decode.cxx b/vcl/source/filter/igif/decode.cxx
index d50ac7c3bd15..4d278d9ddda9 100644
--- a/vcl/source/filter/igif/decode.cxx
+++ b/vcl/source/filter/igif/decode.cxx
@@ -197,6 +197,8 @@ bool GIFLZWDecompressor::ProcessOneCode()
         pE = pTable + nCode;
         do
         {
+            if (pOutBufData == pOutBuf) //can't go back past start
+                return false;
             nOutBufDataLen++;
             *(--pOutBufData) = pE->nData;
             pE = pE->pPrev;