[PATCH] Don't overflow GCTable

[Filipe Cabecinhas]

Hi rafael, dexonsmith,

Bug found with AFL fuzz.

http://reviews.llvm.org/D9361

Files:
  lib/Bitcode/Reader/BitcodeReader.cpp
  test/Bitcode/Inputs/invalid-GCTable-overflow.bc
  test/Bitcode/invalid.test

Index: lib/Bitcode/Reader/BitcodeReader.cpp
===================================================================
--- lib/Bitcode/Reader/BitcodeReader.cpp
+++ lib/Bitcode/Reader/BitcodeReader.cpp
@@ -2992,7 +2992,7 @@
         // FIXME: Change to an error if non-default in 4.0.
         Func->setVisibility(GetDecodedVisibility(Record[7]));
       if (Record.size() > 8 && Record[8]) {
-        if (Record[8]-1 > GCTable.size())
+        if (Record[8]-1 >= GCTable.size())
           return Error("Invalid ID");
         Func->setGC(GCTable[Record[8]-1].c_str());
       }
Index: test/Bitcode/invalid.test
===================================================================
--- test/Bitcode/invalid.test
+++ test/Bitcode/invalid.test
@@ -122,3 +122,8 @@
 RUN:   FileCheck --check-prefix=LOAD-BAD-TYPE %s
 
 LOAD-BAD-TYPE: Load operand is not a pointer type
+
+RUN: not llvm-dis -disable-output %p/Inputs/invalid-GCTable-overflow.bc 2>&1 | \
+RUN:   FileCheck --check-prefix=GCTABLE-OFLOW %s
+
+GCTABLE-OFLOW: Invalid ID

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