[Bitcode] Diagnose errors instead of asserting from bad input

Eventually we can make some of these pass the error along to the caller.

Reports a fatal error if:
We find an invalid abbrev record
We try to get an invalid abbrev number
We can't fill the current word due to an EOF

Fixed an invalid bitcode test to check for output with FileCheck

Bugs found with afl-fuzz

llvm-svn: 226986

1 files changed, 5 insertions, 1 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitstreamReader.cpp b/llvm/lib/Bitcode/Reader/BitstreamReader.cpp
index 5e3232e5313..9d5fab9147a 100644
--- a/llvm/lib/Bitcode/Reader/BitstreamReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitstreamReader.cpp
@@ -170,8 +170,12 @@ unsigned BitstreamCursor::readRecord(unsigned AbbrevID,
   unsigned Code;
   if (CodeOp.isLiteral())
     Code = CodeOp.getLiteralValue();
-  else
+  else {
+    if (CodeOp.getEncoding() == BitCodeAbbrevOp::Array ||
+        CodeOp.getEncoding() == BitCodeAbbrevOp::Blob)
+      report_fatal_error("Abbreviation starts with an Array or a Blob");
     Code = readAbbreviatedField(*this, CodeOp);
+  }
 
   for (unsigned i = 1, e = Abbv->getNumOperandInfos(); i != e; ++i) {
     const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);