I don't think memcmp guarantees that it will not access later bytes in a string if earlier bytes do not match. According to the man page "Both strings are assumed to be n bytes long." So for example if there is a memcmp implementation that compares one word rather than one byte at a time and backtracks to find the return value if there is a mismatch it could seg fault in the following call sites where the allocation for r may be shorter than sz/len.

case cstring:

{ unsigned sz = ((unsigned) *l) + 1; if( memcmp(l, r, sz) ) // first byte checked is the length byte return false; l += sz; r += sz; break; }

case cbindata:

{ int len = binDataCodeToLength(*l) + 1; if( memcmp(l, r, len) ) return false; l += len; r += len; break; }