nvme: Fix ctrl use-after-free during sysfs deletion

In case nvme_sysfs_delete() is called by the user before taking the ctrl
reference count, the ctrl may be freed during the creation and cause the
bug. Take the reference as soon as the controller is externally visible,
which is done by cdev_device_add() in nvme_init_ctrl(). Also take the
reference count at the core layer instead of taking it on each transport
separately.

Signed-off-by: Israel Rukshin <israelr@mellanox.com>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>

6 files changed, 6 insertions, 10 deletions

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 8a7761c3086e..51f80be0fe90 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -4130,6 +4130,7 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,
 	if (ret)
 		goto out_release_instance;
 
+	nvme_get_ctrl(ctrl);
 	cdev_init(&ctrl->cdev, &nvme_dev_fops);
 	ctrl->cdev.owner = ops->module;
 	ret = cdev_device_add(&ctrl->cdev, ctrl->device);
@@ -4148,6 +4149,7 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,
 
 	return 0;
 out_free_name:
+	nvme_put_ctrl(ctrl);
 	kfree_const(ctrl->device->kobj.name);
 out_release_instance:
 	ida_simple_remove(&nvme_instance_ida, ctrl->instance);
diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index 5a70ac395d53..59d2e2bec179 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -3181,10 +3181,7 @@ nvme_fc_init_ctrl(struct device *dev, struct nvmf_ctrl_options *opts,
 		goto fail_ctrl;
 	}
 
-	nvme_get_ctrl(&ctrl->ctrl);
-
 	if (!queue_delayed_work(nvme_wq, &ctrl->connect_work, 0)) {
-		nvme_put_ctrl(&ctrl->ctrl);
 		dev_err(ctrl->ctrl.device,
 			"NVME-FC{%d}: failed to schedule initial connect\n",
 			ctrl->cnum);
@@ -3209,6 +3206,7 @@ fail_ctrl:
 
 	/* initiate nvme ctrl ref counting teardown */
 	nvme_uninit_ctrl(&ctrl->ctrl);
+	nvme_put_ctrl(&ctrl->ctrl);
 
 	/* Remove core ctrl ref. */
 	nvme_put_ctrl(&ctrl->ctrl);
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index ff0bd2d84f3e..4e062c3a84bc 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2802,7 +2802,6 @@ static int nvme_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	dev_info(dev->ctrl.device, "pci function %s\n", dev_name(&pdev->dev));
 
 	nvme_reset_ctrl(&dev->ctrl);
-	nvme_get_ctrl(&dev->ctrl);
 	async_schedule(nvme_async_probe, dev);
 
 	return 0;
diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index 3e85c5cacefd..ca782deea72d 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -2043,8 +2043,6 @@ static struct nvme_ctrl *nvme_rdma_create_ctrl(struct device *dev,
 	dev_info(ctrl->ctrl.device, "new ctrl: NQN \"%s\", addr %pISpcs\n",
 		ctrl->ctrl.opts->subsysnqn, &ctrl->addr);
 
-	nvme_get_ctrl(&ctrl->ctrl);
-
 	mutex_lock(&nvme_rdma_ctrl_mutex);
 	list_add_tail(&ctrl->list, &nvme_rdma_ctrl_list);
 	mutex_unlock(&nvme_rdma_ctrl_mutex);
@@ -2054,6 +2052,7 @@ static struct nvme_ctrl *nvme_rdma_create_ctrl(struct device *dev,
 out_uninit_ctrl:
 	nvme_uninit_ctrl(&ctrl->ctrl);
 	nvme_put_ctrl(&ctrl->ctrl);
+	nvme_put_ctrl(&ctrl->ctrl);
 	if (ret > 0)
 		ret = -EIO;
 	return ERR_PTR(ret);
diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 4b20301e517c..dd569b122a0d 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -2428,8 +2428,6 @@ static struct nvme_ctrl *nvme_tcp_create_ctrl(struct device *dev,
 	dev_info(ctrl->ctrl.device, "new ctrl: NQN \"%s\", addr %pISp\n",
 		ctrl->ctrl.opts->subsysnqn, &ctrl->addr);
 
-	nvme_get_ctrl(&ctrl->ctrl);
-
 	mutex_lock(&nvme_tcp_ctrl_mutex);
 	list_add_tail(&ctrl->list, &nvme_tcp_ctrl_list);
 	mutex_unlock(&nvme_tcp_ctrl_mutex);
@@ -2439,6 +2437,7 @@ static struct nvme_ctrl *nvme_tcp_create_ctrl(struct device *dev,
 out_uninit_ctrl:
 	nvme_uninit_ctrl(&ctrl->ctrl);
 	nvme_put_ctrl(&ctrl->ctrl);
+	nvme_put_ctrl(&ctrl->ctrl);
 	if (ret > 0)
 		ret = -EIO;
 	return ERR_PTR(ret);
diff --git a/drivers/nvme/target/loop.c b/drivers/nvme/target/loop.c
index 4df4ebde208a..a425e2858829 100644
--- a/drivers/nvme/target/loop.c
+++ b/drivers/nvme/target/loop.c
@@ -618,8 +618,6 @@ static struct nvme_ctrl *nvme_loop_create_ctrl(struct device *dev,
 	dev_info(ctrl->ctrl.device,
 		 "new ctrl: \"%s\"\n", ctrl->ctrl.opts->subsysnqn);
 
-	nvme_get_ctrl(&ctrl->ctrl);
-
 	changed = nvme_change_ctrl_state(&ctrl->ctrl, NVME_CTRL_LIVE);
 	WARN_ON_ONCE(!changed);
 
@@ -637,6 +635,7 @@ out_free_queues:
 	kfree(ctrl->queues);
 out_uninit_ctrl:
 	nvme_uninit_ctrl(&ctrl->ctrl);
+	nvme_put_ctrl(&ctrl->ctrl);
 out_put_ctrl:
 	nvme_put_ctrl(&ctrl->ctrl);
 	if (ret > 0)