static int snd_pcm_lib_read_transfer(struct snd_pcm_substream *substream, 
				     unsigned int hwoff,
				     unsigned long data, unsigned int off,
				     snd_pcm_uframes_t frames)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	int err;
	char __user *buf = (char __user *) data + frames_to_bytes(runtime, off);
	if (substream->ops->copy) {
		if ((err = substream->ops->copy(substream, -1, hwoff, buf, frames)) < 0)
			return err;
	} else {
		char *hwbuf = runtime->dma_area + frames_to_bytes(runtime, hwoff);
		if (copy_to_user(buf, hwbuf, frames_to_bytes(runtime, frames)))
			return -EFAULT;
	}
	return 0;
}

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.