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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
CC:     Minwoo Im <minwoo.im.dev@gmail.com>,
        Christoph Hellwig <hch@lst.de>,
        "Sasha Levin" <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.14 070/100] nvme-pci: fix NULL pointer
 dereference in nvme_free_host_mem()
Thread-Topic: [PATCH AUTOSEL for 4.14 070/100] nvme-pci: fix NULL pointer
 dereference in nvme_free_host_mem()
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Date:   Wed, 24 Jan 2018 04:15:00 +0000
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From: Minwoo Im <minwoo.im.dev@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 =3D=3D NULL) && (nr_host_mem_descs !=3D 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>
Signed-off-by: Sasha Levin <alexander.levin@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 =3D NULL;
+	dev->nr_host_mem_descs =3D 0;
 }
=20
 static int __nvme_alloc_host_mem(struct nvme_dev *dev, u64 preferred,
--=20
2.11.0