breaking alsa

breaking_alsa.c

// Problem solved: ok very silly. I used snd_pcm_hw_params_alloca, which allocates on stack.
// Use snd_pcm_hw_params_malloc instead
// oops


// Reference: https://gist.github.com/ghedo/963382/815c98d1ba0eda1b486eb9d80d9a91a81d995283

// This function used to corrupts the memory
void init_params (snd_pcm_t **pcm_handle, snd_pcm_hw_params_t **params)
{
    // https://www.alsa-project.org/alsa-doc/alsa-lib/group___p_c_m___h_w___params.html#ga06b83cb9a788f99b7b09b570b4355cee
    //snd_pcm_hw_params_alloca(params);
    snd_pcm_hw_params_malloc(params);
    // https://www.alsa-project.org/alsa-doc/alsa-lib/group___p_c_m___h_w___params.html#ga6e2dd8efbb7a4084bd05e6cc458d84f7
    snd_pcm_hw_params_any(*pcm_handle, *params);
}

// Function to display the corruption
void corruption_test()
{
    unsigned rc;
    
    // Obtain handle to PCM device
    snd_pcm_t *pcm_handle;
    if (rc = snd_pcm_open(&pcm_handle, PCM_DEVICE, SND_PCM_STREAM_PLAYBACK, 0) < 0){
	printf("ERROR: Can't open \"%s\" PCM device. %s\n", PCM_DEVICE, snd_strerror(rc));
        exit(1);
    }

#ifndef BROKEN_FUNC
    // Initialize params, works fine like this
    snd_pcm_hw_params_t *params;
    snd_pcm_hw_params_alloca(&params);
    snd_pcm_hw_params_any(pcm_handle, params);
#else
    // HERE LIES THE PROBLEM
    // Initialize params, when done like this, snd_pcm_hw_params_set_access 
    //  causes *** stack smashing detected ***: <unknown> terminated
    snd_pcm_hw_params_t *params;
    init_params(&pcm_handle, &params);
#endif

    if (rc = snd_pcm_hw_params_set_access(pcm_handle, params, SND_PCM_ACCESS_RW_INTERLEAVED) < 0) {
        printf("ERROR: Can't set interleaved mode. %s\n", snd_strerror(rc));
        exit(1);
    }

    snd_pcm_access_t acc;
    snd_pcm_hw_params_get_access(params, &acc);
    printf("access: %s\n", acc == SND_PCM_ACCESS_RW_INTERLEAVED ? "interleaved" : "other");
}