nvme-pci: fix NULL pointer dereference in nvme_free_host_mem()

Following condition which will cause NULL pointer dereference will occur in nvme_free_host_mem() when it tries to remove pci device via nvme_remove() especially after a failure of host memory allocation for HMB.

    "(host_mem_descs == NULL) && (nr_host_mem_descs != 0)"

It's because __nr_host_mem_descs__ is not cleared to 0 unlike __host_mem_descs__ is so.

Signed-off-by Minwoo Im <minwoo.im.dev at gmail.com>

---
 drivers/nvme/host/pci.c | 1 +
 1 file changed, 1 insertion(+)

drivers/nvme/host/pci.c +1 -1

index 6173747..f5800c3 100644
@@ -1759,6 +1759,7 @@ static void nvme_free_host_mem(struct nvme_dev *dev)
                        dev->nr_host_mem_descs * sizeof(*dev->host_mem_descs),
                        dev->host_mem_descs, dev->host_mem_descs_dma);
        dev->host_mem_descs = NULL;
+       dev->nr_host_mem_descs = 0;
 }
 
 static int __nvme_alloc_host_mem(struct nvme_dev *dev, u64 preferred,
--

2.7.4