Assert objnum non-zero in ReplaceIndirectObjectIfHigherGeneration()

core/fpdfapi/parser/cfdf_document.cpp

Index: core/fpdfapi/parser/cfdf_document.cpp
diff --git a/core/fpdfapi/parser/cfdf_document.cpp b/core/fpdfapi/parser/cfdf_document.cpp
index d39ec31d3cf55ffd3da59665cd0e3c749a47362e..bcaa9daec3630ca7fb7dae77c55ffa5bcaae9ba0 100644
--- a/core/fpdfapi/parser/cfdf_document.cpp
+++ b/core/fpdfapi/parser/cfdf_document.cpp
@@ -58,6 +58,9 @@ void CFDF_Document::ParseStream(IFX_SeekableReadStream* pFile, bool bOwnFile) {
     CFX_ByteString word = parser.GetNextWord(&bNumber);
     if (bNumber) {
       uint32_t objnum = FXSYS_atoui(word.c_str());
+      if (!objnum)
+        break;
+
       word = parser.GetNextWord(&bNumber);
       if (!bNumber)
         break;