memory leak or some other problem in C++ and vector of strings

i keep getting memory leaks everytime I run this function in a loop:

uint32_t *padMessages(uint32_t *messages, const std::vector<std::string> &words) 
{
    uint32_t output[16];
    uint32_t size = words.size();
    uint32_t i, x, y;

    messages = (uint32_t *)malloc(16 * size * sizeof(uint32_t));

    x = 0;
    for(i = 0; i < size; i++) {
        padMessage((uint32_t *)_strdup(words[i].c_str()), output, strlen((const char *)words[i].c_str()) * 8);
        for(y = 0; y < 16; y++) {
            messages[x] = output[y];
            x++;
        }
    }

    return messages;
}

the code calling this function is

do {
    for(i=0 ; i<len ; i++) 
        temp[i] = letters[entry[i]];
    temp[len] = '\0';

    // store generated word to words vector
    words[array_count] = temp;

    // increment vector counter and total word count
    array_count++;
    word_count++;

    if(array_count == 100000) {
        // reinitialize array_count
        array_count = 0;

        // pad messages
        messages = padMessages(messages, words);

        free(messages);
        free(result);

        std::vector<std::string>().swap(words);
        words.resize(100000);
    }
    for(i=0 ; i<len && ++entry[i] == nbletters; 开发者_如何转开发i++) entry[i] = 0;
} while(i<len);

where is my memory leaking?

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This:

(uint32_t *)_strdup(words[i].c_str())

...allocates memory dynamically, and I don't see any matching call to free for the memory allocated.

I'd use std::string throughout.

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You are calling strdup in the loop in the top function and you are never free'ing those strings you are allocating.

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My guess would be that the memory allocated by _strdup isn't freed.