[PATCH] [Bitcode reader] Fix a few assertions when reading invalid files

[Filipe Cabecinhas]

Hi rafael,

When creating {insert,extract}value instructions from a BitcodeReader, we
weren't verifying the fields were valid.

Bugs found with afl-fuzz

http://reviews.llvm.org/D7325

Files:
  lib/Bitcode/Reader/BitcodeReader.cpp
  test/Bitcode/Inputs/invalid-extractval-array-idx.bc
  test/Bitcode/Inputs/invalid-extractval-struct-idx.bc
  test/Bitcode/Inputs/invalid-extractval-too-many-idxs.bc
  test/Bitcode/Inputs/invalid-insertval-array-idx.bc
  test/Bitcode/Inputs/invalid-insertval-struct-idx.bc
  test/Bitcode/Inputs/invalid-insertval-too-many-idxs.bc
  test/Bitcode/invalid.test

Index: lib/Bitcode/Reader/BitcodeReader.cpp
===================================================================
--- lib/Bitcode/Reader/BitcodeReader.cpp
+++ lib/Bitcode/Reader/BitcodeReader.cpp
@@ -2793,12 +2793,27 @@
         return Error("Invalid record");
 
       SmallVector<unsigned, 4> EXTRACTVALIdx;
+      Type *CurTy = Agg->getType();
       for (unsigned RecSize = Record.size();
            OpNum != RecSize; ++OpNum) {
+        bool IsArray = CurTy->isArrayTy();
+        bool IsStruct = CurTy->isStructTy();
         uint64_t Index = Record[OpNum];
+
+        if (!IsStruct && !IsArray)
+          return Error("EXTRACTVAL: Invalid type");
         if ((unsigned)Index != Index)
           return Error("Invalid value");
+        if (IsStruct && Index >= CurTy->subtypes().size())
+          return Error("EXTRACTVAL: Invalid struct index");
+        if (IsArray && Index >= CurTy->getArrayNumElements())
+          return Error("EXTRACTVAL: Invalid array index");
         EXTRACTVALIdx.push_back((unsigned)Index);
+
+        if (IsStruct)
+          CurTy = CurTy->subtypes()[Index];
+        else
+          CurTy = CurTy->subtypes()[0];
       }
 
       I = ExtractValueInst::Create(Agg, EXTRACTVALIdx);
@@ -2817,12 +2832,29 @@
         return Error("Invalid record");
 
       SmallVector<unsigned, 4> INSERTVALIdx;
+      Type *CurTy = Agg->getType();
       for (unsigned RecSize = Record.size();
            OpNum != RecSize; ++OpNum) {
+        bool IsArray = CurTy->isArrayTy();
+        bool IsStruct = CurTy->isStructTy();
         uint64_t Index = Record[OpNum];
+
+        if (!IsStruct && !IsArray)
+          return Error("INSERTVAL: Invalid type");
+        if (!CurTy->isStructTy() && !CurTy->isArrayTy())
+          return Error("Invalid type");
         if ((unsigned)Index != Index)
           return Error("Invalid value");
+        if (IsStruct && Index >= CurTy->subtypes().size())
+          return Error("INSERTVAL: Invalid struct index");
+        if (IsArray && Index >= CurTy->getArrayNumElements())
+          return Error("INSERTVAL: Invalid array index");
+
         INSERTVALIdx.push_back((unsigned)Index);
+        if (IsStruct)
+          CurTy = CurTy->subtypes()[Index];
+        else
+          CurTy = CurTy->subtypes()[0];
       }
 
       I = InsertValueInst::Create(Agg, Val, INSERTVALIdx);
Index: test/Bitcode/invalid.test
===================================================================
--- test/Bitcode/invalid.test
+++ test/Bitcode/invalid.test
@@ -17,3 +17,24 @@
 BAD-ABBREV-NUMBER: Invalid abbrev number
 BAD-TYPE-TABLE-FORWARD-REF: Invalid TYPE table: Only named structs can be forward referenced
 BAD-BITWIDTH: Bitwidth for integer type out of range
+
+RUN: not llvm-dis -disable-output %p/Inputs/invalid-extractval-array-idx.bc 2>&1 | \
+RUN:   FileCheck --check-prefix=EXTRACT-ARRAY %s
+RUN: not llvm-dis -disable-output %p/Inputs/invalid-extractval-struct-idx.bc 2>&1 | \
+RUN:   FileCheck --check-prefix=EXTRACT-STRUCT %s
+RUN: not llvm-dis -disable-output %p/Inputs/invalid-extractval-too-many-idxs.bc 2>&1 | \
+RUN:   FileCheck --check-prefix=EXTRACT-IDXS %s
+RUN: not llvm-dis -disable-output %p/Inputs/invalid-insertval-array-idx.bc 2>&1 | \
+RUN:   FileCheck --check-prefix=INSERT-ARRAY %s
+RUN: not llvm-dis -disable-output %p/Inputs/invalid-insertval-struct-idx.bc 2>&1 | \
+RUN:   FileCheck --check-prefix=INSERT-STRUCT %s
+RUN: not llvm-dis -disable-output %p/Inputs/invalid-insertval-too-many-idxs.bc 2>&1 | \
+RUN:   FileCheck --check-prefix=INSERT-IDXS %s
+
+
+EXTRACT-ARRAY: EXTRACTVAL: Invalid array index
+EXTRACT-STRUCT: EXTRACTVAL: Invalid struct index
+EXTRACT-IDXS: EXTRACTVAL: Invalid type
+INSERT-ARRAY: INSERTVAL: Invalid array index
+INSERT-STRUCT: INSERTVAL: Invalid struct index
+INSERT-IDXS: INSERTVAL: Invalid type

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