[PATCH AUTOSEL for 4.14 070/100] nvme-pci: fix NULL pointer dereference in nvme_free_host_mem()

[Sasha Levin]

From: Minwoo Im <minwoo.im....@gmail.com>

[ Upstream commit 7e5dd57ef3081ff6c03908d786ed5087f6fbb7ae ]

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....@gmail.com>
Signed-off-by: Christoph Hellwig <h...@lst.de>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
---
 drivers/nvme/host/pci.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 5dae650438c1..cdd2fd509ddc 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1617,6 +1617,7 @@ 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,
-- 
2.11.0