void esp_dma_enable(ESPState *s, int irq, int level)
{
    if (level) {
        s->dma_enabled = 1;
        trace_esp_dma_enable();
        if (s->dma_cb) {
            s->dma_cb(s);
            s->dma_cb = NULL;
        }
    } else {
        trace_esp_dma_disable();
        s->dma_enabled = 0;
    }
}

The product writes data past the end, or before the beginning, of the intended buffer.