A DMA reentrancy issue was found in the Tulip device emulation in QEMU. When Tulip reads or writes to the rx/tx descriptor or copies the rx/tx frame it doesn't check whether the destination address is its own MMIO address. This can cause the device to trigger MMIO handlers multiple times possibly leading to a stack or heap overflow. A malicious guest could use this flaw to crash the QEMU process on the host resulting in a denial of service condition.