fix gif import crash

Change-Id: I3a5e0efef6843fb8f8b485fa2369ac5b99513c31

2 files changed, 2 insertions, 0 deletions

diff --git a/vcl/qa/cppunit/graphicfilter/data/gif/pass/crash-1.gif b/vcl/qa/cppunit/graphicfilter/data/gif/pass/crash-1.gif
new file mode 100644
index 000000000000..860f9e1d8fae
--- /dev/null
+++ b/vcl/qa/cppunit/graphicfilter/data/gif/pass/crash-1.gif
diff --git a/vcl/source/filter/igif/decode.cxx b/vcl/source/filter/igif/decode.cxx
index 46a666f812ae..1b18f5ee134a 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;