nvme-pci: fix freeing of the HMB descriptor table

In the Linux kernel, the following vulnerability has been resolved: nvme-pci: fix freeing of the HMB descriptor table The HMB descriptor table is sized to the maximum number of descriptors that could be used for a given device, but __nvme_alloc_host_mem could break out of the loop earlier on memory allocation failure and end up using less descriptors than planned for, which leads to an incorrect size passed to dma_free_coherent. In practice this was not showing up because the number of descriptors tends to be low and the dma coherent allocator always allocates and frees at least a page.