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

minwooim · Christoph Hellwig · commit 7e5dd57ef308 · 2017-11-28T08:49:26.000-08:00
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) &amp;&amp; (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 &lt;minwoo.im.dev@gmail.com&gt;
Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
@@ -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,

Original file line number	Diff line number	Diff line change
`@@ -1759,6 +1759,7 @@ static void nvme_free_host_mem(struct nvme_dev *dev)`
`1759`	`1759`	`dev->nr_host_mem_descs * sizeof(*dev->host_mem_descs),`
`1760`	`1760`	`dev->host_mem_descs, dev->host_mem_descs_dma);`
`1761`	`1761`	`dev->host_mem_descs = NULL;`
	`1762`	`+ dev->nr_host_mem_descs = 0;`
`1762`	`1763`	`}`
`1763`	`1764`
`1764`	`1765`	`static int __nvme_alloc_host_mem(struct nvme_dev *dev, u64 preferred,`