have_pid = pid != 0 && pid != getpid();
if (n_fds > 0 || have_pid) {
- msghdr.msg_controllen = CMSG_SPACE(sizeof(int) * n_fds) +
- CMSG_SPACE(sizeof(struct ucred) * have_pid);
+ /* CMSG_SPACE(0) may return value different then zero, which results in miscalculated controllen. */
+ msghdr.msg_controllen = (n_fds ? CMSG_SPACE(sizeof(int) * n_fds) : 0) +
+ CMSG_SPACE(sizeof(struct ucred)) * have_pid;
msghdr.msg_control = alloca(msghdr.msg_controllen);
cmsg = CMSG_FIRSTHDR(&msghdr);