device: 0.858 vnc: 0.750 network: 0.682 graphic: 0.585 semantic: 0.454 files: 0.398 other: 0.374 PID: 0.351 socket: 0.328 boot: 0.304 permissions: 0.144 debug: 0.121 performance: 0.087 KVM: 0.076 nvme: DMA reentrancy issue leads to use-after-free (CVE-2021-3929) Description of problem: A DMA reentrancy issue was found in the NVM Express Controller (NVMe) emulation. Functions dma_buf_write() or dma_buf_read() in hw/nvme/ctrl.c:nvme_tx() can be called without checking if the destination region overlaps with device's MMIO. This is similar to CVE-2021-3750 (https://gitlab.com/qemu-project/qemu/-/issues/541) and, just like it, when the reentrancy write triggers the reset function nvme_ctrl_reset(), data structs will be freed leading to a use-after-free issue. A malicious guest could use this flaw to crash the QEMU process on the host, resulting in a denial of service condition or, potentially, executing arbitrary code within the context of the QEMU process on the host. This issue was reported by Qiuhao Li.