static void completionCallback(const char *buf, linenoiseCompletions *lc) {
    size_t startpos = 0;
    int mask;
    int i;
    size_t matchlen;
    sds tmp;

    if (strncasecmp(buf,"help ",5) == 0) {
        startpos = 5;
        while (isspace(buf[startpos])) startpos++;
        mask = CLI_HELP_COMMAND | CLI_HELP_GROUP;
    } else {
        mask = CLI_HELP_COMMAND;
    }

    for (i = 0; i < helpEntriesLen; i++) {
        if (!(helpEntries[i].type & mask)) continue;

        matchlen = strlen(buf+startpos);
        if (strncasecmp(buf+startpos,helpEntries[i].full,matchlen) == 0) {
            tmp = sdsnewlen(buf,startpos);
            tmp = sdscat(tmp,helpEntries[i].full);
            linenoiseAddCompletion(lc,tmp);
            sdsfree(tmp);
        }
    }
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.