PVS-Studio warning V579 for Firebird

ULONG convert(const ULONG srcLen,
              const UCHAR* src,
              const ULONG dstLen,
              UCHAR* dst,
              ULONG* badInputPos = NULL,
              bool ignoreTrailingSpaces = false);

string IntlUtil::escapeAttribute(....)
{
  ....
  ULONG l;
  UCHAR* uc = (UCHAR*)(&l);
  const ULONG uSize =
    cs->getConvToUnicode().convert(size, p, sizeof(uc), uc);
  ....
}

This suspicious code was found in Firebird project by PVS-Studio static code analyzer.
Warning message is:
V579 The convert function receives the pointer and its size as arguments. It is possibly a mistake. Inspect the third argument. intlutil.cpp 668

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/