Use common parse routine to read alignment values from bitcode

While fuzzing LLVM bitcode files, I discovered that (1) the bitcode reader doesn't check that alignments are no larger than 2**29; (2) downstream code doesn't check the range; and (3) for values out of range, corresponding large memory requests (based on alignment size) will fail. This code fixes the bitcode reader to check for valid alignments, fixing this problem.

This CL fixes alignment value on global variables, functions, and instructions: alloca, load, load atomic, store, store atomic.

Patch by Karl Schimpf (kschimpf@google.com).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230180 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/IR/Value.h b/include/llvm/IR/Value.h
index 517dd26d3007d81c5eeb70416e08b66ed83454bc..b7213a67220cf78f36f0d2fd598fbc6934a7cfc4 100644 (file)
--- a/include/llvm/IR/Value.h
+++ b/include/llvm/IR/Value.h
@@ -469,7 +469,8 @@ public:
   ///
   /// This is the greatest alignment value supported by load, store, and alloca
   /// instructions, and global values.
-  static const unsigned MaximumAlignment = 1u << 29;
+  static const unsigned MaxAlignmentExponent = 29;
+  static const unsigned MaximumAlignment = 1u << MaxAlignmentExponent;
 
   /// \brief Mutate the type of this Value to be of the specified type.
   ///

diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index bb6ba6fc6e1c2daa4c2dfd5bb1c72fa720779e6b..3b3a6eb43d11b83b41744e98150c5511a0076a03 100644 (file)
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -794,6 +794,16 @@ static Attribute::AttrKind GetAttrFromCode(uint64_t Code) {
   }
 }
 
+std::error_code BitcodeReader::parseAlignmentValue(uint64_t Exponent,
+                                                   unsigned &Alignment) {
+  // Note: Alignment in bitcode files is incremented by 1, so that zero
+  // can be used for default alignment.
+  if (Exponent > Value::MaxAlignmentExponent + 1)
+    return Error("Invalid alignment value");
+  Alignment = (1 << static_cast<unsigned>(Exponent)) >> 1;
+  return std::error_code();
+}
+
 std::error_code BitcodeReader::ParseAttrKind(uint64_t Code,
                                              Attribute::AttrKind *Kind) {
   *Kind = GetAttrFromCode(Code);
@@ -2462,7 +2472,9 @@ std::error_code BitcodeReader::ParseModule(bool Resume) {
       bool isConstant = Record[1];
       uint64_t RawLinkage = Record[3];
       GlobalValue::LinkageTypes Linkage = getDecodedLinkage(RawLinkage);
-      unsigned Alignment = (1 << Record[4]) >> 1;
+      unsigned Alignment;
+      if (std::error_code EC = parseAlignmentValue(Record[4], Alignment))
+        return EC;
       std::string Section;
       if (Record[5]) {
         if (Record[5]-1 >= SectionTable.size())
@@ -2542,7 +2554,10 @@ std::error_code BitcodeReader::ParseModule(bool Resume) {
       Func->setLinkage(getDecodedLinkage(RawLinkage));
       Func->setAttributes(getAttributes(Record[4]));
 
-      Func->setAlignment((1 << Record[5]) >> 1);
+      unsigned Alignment;
+      if (std::error_code EC = parseAlignmentValue(Record[5], Alignment))
+        return EC;
+      Func->setAlignment(Alignment);
       if (Record[6]) {
         if (Record[6]-1 >= SectionTable.size())
           return Error("Invalid ID");
@@ -3539,12 +3554,17 @@ std::error_code BitcodeReader::ParseFunctionBody(Function *F) {
         dyn_cast_or_null<PointerType>(getTypeByID(Record[0]));
       Type *OpTy = getTypeByID(Record[1]);
       Value *Size = getFnValueByID(Record[2], OpTy);
-      unsigned AlignRecord = Record[3];
-      bool InAlloca = AlignRecord & (1 << 5);
-      unsigned Align = AlignRecord & ((1 << 5) - 1);
+      uint64_t AlignRecord = Record[3];
+      const uint64_t InAllocaMask = uint64_t(1) << 5;
+      bool InAlloca = AlignRecord & InAllocaMask;
+      unsigned Align;
+      if (std::error_code EC =
+          parseAlignmentValue(AlignRecord & ~InAllocaMask, Align)) {
+        return EC;
+      }
       if (!Ty || !Size)
         return Error("Invalid record");
-      AllocaInst *AI = new AllocaInst(Ty->getElementType(), Size, (1 << Align) >> 1);
+      AllocaInst *AI = new AllocaInst(Ty->getElementType(), Size, Align);
       AI->setUsedWithInAlloca(InAlloca);
       I = AI;
       InstructionList.push_back(I);
@@ -3556,8 +3576,10 @@ std::error_code BitcodeReader::ParseFunctionBody(Function *F) {
       if (getValueTypePair(Record, OpNum, NextValueNo, Op) ||
           OpNum+2 != Record.size())
         return Error("Invalid record");
-
-      I = new LoadInst(Op, "", Record[OpNum+1], (1 << Record[OpNum]) >> 1);
+      unsigned Align;
+      if (std::error_code EC = parseAlignmentValue(Record[OpNum], Align))
+        return EC;
+      I = new LoadInst(Op, "", Record[OpNum+1], Align);
       InstructionList.push_back(I);
       break;
     }
@@ -3577,8 +3599,10 @@ std::error_code BitcodeReader::ParseFunctionBody(Function *F) {
         return Error("Invalid record");
       SynchronizationScope SynchScope = GetDecodedSynchScope(Record[OpNum+3]);
 
-      I = new LoadInst(Op, "", Record[OpNum+1], (1 << Record[OpNum]) >> 1,
-                       Ordering, SynchScope);
+      unsigned Align;
+      if (std::error_code EC = parseAlignmentValue(Record[OpNum], Align))
+        return EC;
+      I = new LoadInst(Op, "", Record[OpNum+1], Align, Ordering, SynchScope);
       InstructionList.push_back(I);
       break;
     }
@@ -3590,8 +3614,10 @@ std::error_code BitcodeReader::ParseFunctionBody(Function *F) {
                     cast<PointerType>(Ptr->getType())->getElementType(), Val) ||
           OpNum+2 != Record.size())
         return Error("Invalid record");
-
-      I = new StoreInst(Val, Ptr, Record[OpNum+1], (1 << Record[OpNum]) >> 1);
+      unsigned Align;
+      if (std::error_code EC = parseAlignmentValue(Record[OpNum], Align))
+        return EC;
+      I = new StoreInst(Val, Ptr, Record[OpNum+1], Align);
       InstructionList.push_back(I);
       break;
     }
@@ -3613,8 +3639,10 @@ std::error_code BitcodeReader::ParseFunctionBody(Function *F) {
       if (Ordering != NotAtomic && Record[OpNum] == 0)
         return Error("Invalid record");
 
-      I = new StoreInst(Val, Ptr, Record[OpNum+1], (1 << Record[OpNum]) >> 1,
-                        Ordering, SynchScope);
+      unsigned Align;
+      if (std::error_code EC = parseAlignmentValue(Record[OpNum], Align))
+        return EC;
+      I = new StoreInst(Val, Ptr, Record[OpNum+1], Align, Ordering, SynchScope);
       InstructionList.push_back(I);
       break;
     }

diff --git a/lib/Bitcode/Reader/BitcodeReader.h b/lib/Bitcode/Reader/BitcodeReader.h
index 5090be48450ebc9306fd7baa995a61d45acce99b..9803e78b929a0430cfa2bded645af9cfb7bc9955 100644 (file)
--- a/lib/Bitcode/Reader/BitcodeReader.h
+++ b/lib/Bitcode/Reader/BitcodeReader.h
@@ -335,6 +335,10 @@ private:
     return getFnValueByID(ValNo, Ty);
   }
 
+  /// Converts alignment exponent (i.e. power of two (or zero)) to the
+  /// corresponding alignment to use. If alignment is too large, returns
+  /// a corresponding error code.
+  std::error_code parseAlignmentValue(uint64_t Exponent, unsigned &Alignment);
   std::error_code ParseAttrKind(uint64_t Code, Attribute::AttrKind *Kind);
   std::error_code ParseModule(bool Resume);
   std::error_code ParseAttributeBlock();

diff --git a/test/Bitcode/Inputs/invalid-align.bc b/test/Bitcode/Inputs/invalid-align.bc
new file mode 100644 (file)
index 0000000..e84fa6c
Binary files /dev/null and b/test/Bitcode/Inputs/invalid-align.bc differ

diff --git a/test/Bitcode/invalid.test b/test/Bitcode/invalid.test
index 84bc9278d9107b5562c38b07c77cdefc15f7dcb0..fb818884eed8574379b2c026159660a468ddb5a9 100644 (file)
--- a/test/Bitcode/invalid.test
+++ b/test/Bitcode/invalid.test
@@ -10,6 +10,8 @@ RUN: not llvm-dis -disable-output %p/Inputs/invalid-type-table-forward-ref.bc 2>
 RUN:   FileCheck --check-prefix=BAD-TYPE-TABLE-FORWARD-REF %s
 RUN: not llvm-dis -disable-output %p/Inputs/invalid-bitwidth.bc 2>&1 | \
 RUN:   FileCheck --check-prefix=BAD-BITWIDTH %s
+RUN: not llvm-dis -disable-output %p/Inputs/invalid-align.bc  2>&1 | \
+RUN:   FileCheck --check-prefix=BAD-ALIGN %s
 
 INVALID-ENCODING: Invalid encoding
 BAD-ABBREV: Abbreviation starts with an Array or a Blob
@@ -17,6 +19,7 @@ UNEXPECTED-EOF: Unexpected end of file
 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
+BAD-ALIGN: Invalid alignment value
 
 RUN: not llvm-dis -disable-output %p/Inputs/invalid-extractval-array-idx.bc 2>&1 | \
 RUN:   FileCheck --check-prefix=EXTRACT-ARRAY %s