PVS-Studio warning V512 for smtp_ssl

void MD5::finalize () {
  ...
  uint1 buffer[64];
  ...
  // Zeroize sensitive information
  memset (buffer, 0, sizeof(*buffer));
  ...
}

Most likely this is what should be written here: memset (buffer, 0, sizeof(buffer));

This suspicious code was found in smtp_ssl project by PVS-Studio static code analyzer.
Warning message is:
V512 A call of the 'memset' function will lead to a buffer overflow or underflow. CSmtp md5.cpp 212

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/