Fix a crash in MallocOverflowSecurityChecker. Patch by Lei Zhang.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@140648 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/StaticAnalyzer/Checkers/MallocOverflowSecurityChecker.cpp b/lib/StaticAnalyzer/Checkers/MallocOverflowSecurityChecker.cpp
index 983252c..0f6b621 100644
--- a/lib/StaticAnalyzer/Checkers/MallocOverflowSecurityChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/MallocOverflowSecurityChecker.cpp
@@ -244,6 +244,8 @@
 
           // Get the name of the callee. If it's a builtin, strip off the prefix.
           IdentifierInfo *FnInfo = FD->getIdentifier();
+          if (!FnInfo)
+            return;
 
           if (FnInfo->isStr ("malloc") || FnInfo->isStr ("_MALLOC")) {
             if (TheCall->getNumArgs() == 1)