[DWP][DWARF] Detect and error on debug info offset overflow

[ayermolo]

Summary

Right now we silently overflow uint32_t for debug_indfo sections. Added a check
and error out.

[ayermolo]

removed header

[ayermolo]

@dblaikie Not sure how to test this code path with unit test.

[ayermolo]

@dblaikie accidentally pushed this while pushing https://reviews.llvm.org/D130335.
Want me to revert this commit?

[MaskRay]

llvm/lib/DWP/DWP.cpp

684

No capitalization or trailing period for diagnostics: https://llvm.org/docs/CodingStandards.html#error-and-warning-messages

At least the following DWPError follows this generic guideline

[ayermolo]

llvm/lib/DWP/DWP.cpp

684

ok, will revert and put up a new diff with error message that follows the guideline.

[ayermolo]

D130395

llvm/lib/DWP/DWP.cpp

 #include "llvm/DWP/DWP.h"
 #include "llvm/DWP/DWPError.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCObjectFileInfo.h"
 #include "llvm/MC/MCTargetOptionsCommandFlags.h"
 #include "llvm/Object/Decompressor.h"
 #include "llvm/Object/ELFObjectFile.h"
 #include "llvm/Support/MemoryBuffer.h"
+#include <limits>
 
 using namespace llvm;
 using namespace llvm::object;
 
 static mc::RegisterMCTargetOptionsFlags MCTargetOptionsFlags;
 
 // Returns the size of debug_str_offsets section headers in bytes.
 static uint64_t debugStrOffsetsHeaderSize(DataExtractor StrOffsetsData,
if (CurCUIndexSection.empty()) {
             FoundCUUnit = true;
           } else if (Header.UnitType == dwarf::DW_UT_split_type) {
             auto P = TypeIndexEntries.insert(
                 std::make_pair(*Header.Signature, Entry));
             if (!P.second)
               continue;
           }
           Out.emitBytes(Info.substr(UnitOffset - C.Length, C.Length));
+          if (std::numeric_limits<uint32_t>::max() - InfoSectionOffset < C.Length)
+            return make_error<DWPError>("Debug Info offset greater then 4GB.");
+
           InfoSectionOffset += C.Length;
         }
       }
 
       if (!FoundCUUnit)
         return make_error<DWPError>("no compile unit found in file: " + Input);
 
       if (IndexVersion == 2) {