diff options
| -rw-r--r-- | src/google/protobuf/io/coded_stream.h | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/src/google/protobuf/io/coded_stream.h b/src/google/protobuf/io/coded_stream.h index c81a33ac6..7b742a18e 100644 --- a/src/google/protobuf/io/coded_stream.h +++ b/src/google/protobuf/io/coded_stream.h @@ -985,7 +985,11 @@ inline std::pair<uint32, bool> CodedInputStream::ReadTagWithCutoff( } // Slow path last_tag_ = ReadTagFallback(first_byte_or_zero); - return std::make_pair(last_tag_, static_cast<uint32>(last_tag_ - 1) < cutoff); + // If last_tag_ == 0 we want to return { 0, false } so the following overflow is intended. + // We use __builtin_add_overflow to appease the sub-overflow UB sanitizer. + uint32_t last_tag_minus_one; + __builtin_add_overflow(last_tag_, -1, &last_tag_minus_one); + return std::make_pair(last_tag_, last_tag_minus_one < cutoff); } inline bool CodedInputStream::LastTagWas(uint32 expected) { |