From: Minwoo Im <minwoo.im.dev@gmail.com>
Date: Sat, 25 Nov 2017 03:03:00 +0900
Subject: nvme-pci: fix NULL pointer dereference in nvme_free_host_mem()
Patch-mainline: v4.15-rc2
Git-commit: 7e5dd57ef3081ff6c03908d786ed5087f6fbb7ae
References: FATE#323952, FATE#322506

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@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
---
 drivers/nvme/host/pci.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1759,6 +1759,7 @@ static void nvme_free_host_mem(struct nv
 			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,