[Sample Profile Reader] Fix potential integer overflow/infinite loop bug in sample profile reader

[huangjd]

Summary

Change loop induction variable type to match the type of "SIZE" where it's compared against, to prevent infinite loop caused by overflow wraparound if there are more than 2^32 samples

[wenlei]

The change makes sense since the fields are actually 64-bit ones. But which one of the loops did you run into issue with? Curious which part is overflowing int32.

[huangjd]

It is more of a precaution, but I did come across very large afdo profiles.

llvm/lib/ProfileData/SampleProfReader.cpp

std::error_code SampleProfileReaderExtBinaryBase::readFuncOffsetTable() {
   FuncOffsetTable.reserve(*Size);
 
   if (FuncOffsetsOrdered) {
     OrderedFuncOffsets =
         std::make_unique<std::vector<std::pair<SampleContext, uint64_t>>>();
     OrderedFuncOffsets->reserve(*Size);
   }
 
-  for (uint32_t I = 0; I < *Size; ++I) {
+  for (uint64_t I = 0; I < *Size; ++I) {
     auto FContext(readSampleContextFromTable());
     if (std::error_code EC = FContext.getError())
       return EC;
 
     auto Offset = readNumber<uint64_t>();
     if (std::error_code EC = Offset.getError())
       return EC;
 
if (FixedLengthMD5) {
     // check using the size of NameTable.
     NameTable.resize(*Size + NameTable.size());
 
     MD5NameMemStart = Data;
     Data = Data + (*Size) * sizeof(uint64_t);
     return sampleprof_error::success;
   }
   NameTable.reserve(*Size);
-  for (uint32_t I = 0; I < *Size; ++I) {
+  for (uint64_t I = 0; I < *Size; ++I) {
     auto FID = readNumber<uint64_t>();
     if (std::error_code EC = FID.getError())
       return EC;
     MD5StringBuf->push_back(std::to_string(*FID));
     // NameTable is a vector of StringRef. Here it is pushing back a
     // StringRef initialized with the last string in MD5stringBuf.
     NameTable.push_back(MD5StringBuf->back());
   }
SampleProfileReaderExtBinaryBase::readFuncMetadata(bool ProfileHasAttribute) {
   return sampleprof_error::success;
 }
 
 std::error_code SampleProfileReaderCompactBinary::readNameTable() {
   auto Size = readNumber<uint64_t>();
   if (std::error_code EC = Size.getError())
     return EC;
   NameTable.reserve(*Size);
-  for (uint32_t I = 0; I < *Size; ++I) {
+  for (uint64_t I = 0; I < *Size; ++I) {
     auto FID = readNumber<uint64_t>();
     if (std::error_code EC = FID.getError())
       return EC;
     NameTable.push_back(std::to_string(*FID));
   }
   return sampleprof_error::success;
 }
 
SampleProfileReaderExtBinaryBase::readSecHdrTableEntry(uint32_t Idx) {
   return sampleprof_error::success;
 }
 
 std::error_code SampleProfileReaderExtBinaryBase::readSecHdrTable() {
   auto EntryNum = readUnencodedNumber<uint64_t>();
   if (std::error_code EC = EntryNum.getError())
     return EC;
 
-  for (uint32_t i = 0; i < (*EntryNum); i++)
+  for (uint64_t i = 0; i < (*EntryNum); i++)
     if (std::error_code EC = readSecHdrTableEntry(i))
       return EC;
 
   return sampleprof_error::success;
 }
 
 std::error_code SampleProfileReaderExtBinaryBase::readHeader() {
   const uint8_t *BufStart =
const uint8_t *TableStart =
       *TableOffset;
   Data = TableStart;
 
   auto Size = readNumber<uint64_t>();
   if (std::error_code EC = Size.getError())
     return EC;
 
   FuncOffsetTable.reserve(*Size);
-  for (uint32_t I = 0; I < *Size; ++I) {
+  for (uint64_t I = 0; I < *Size; ++I) {
     auto FName(readStringFromTable());
     if (std::error_code EC = FName.getError())
       return EC;
 
     auto Offset = readNumber<uint64_t>();
     if (std::error_code EC = Offset.getError())
       return EC;