[PATCH] nvmet: use the enabled transport when disabling a port

[Rongzheng Wang]

nvmet_disable_port() looks up the transport from the current
disc_addr.trtype, while nvmet_enable_port() records the transport in
port->tr_ops.  If trtype is changed while a port is being enabled, the
port can be removed through a different transport, passing the private
data of the original transport to the wrong ->remove_port().

The same mismatch is reachable with loop and RDMA: loop add_port()
leaves port->priv NULL, and RDMA remove_port() dereferences it.

Use port->tr_ops for removal and serialize trtype changes with
nvmet_config_sem in nvmet_addr_trtype_store(), so the transport that
added the port is also the one that removes it.

Fixes: 8f000cac6e7a ("nvmet-rdma: add a NVMe over Fabrics RDMA target driver")
Reported-by: syzbot+c98b21427617af7f547a at syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=c98b21427617af7f547a
Link: https://lore.kernel.org/all/6acbc835.a150a118.27e199.003c.GAE@google.com/T/
Signed-off-by: Rongzheng Wang <testwrzwrz at gmail.com>
---
 drivers/nvme/target/configfs.c | 16 ++++++++++++----
 drivers/nvme/target/core.c     |  8 +++++---
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index b03b5d1c2dc3..955f2b127970 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -387,10 +387,15 @@ static ssize_t nvmet_addr_trtype_store(struct config_item *item,
 		const char *page, size_t count)
 {
 	struct nvmet_port *port = to_nvmet_port(item);
+	ssize_t ret = count;
 	int i;
 
-	if (nvmet_is_port_enabled(port, __func__))
-		return -EACCES;
+	down_write(&nvmet_config_sem);
+
+	if (nvmet_is_port_enabled(port, __func__)) {
+		ret = -EACCES;
+		goto out;
+	}
 
 	for (i = 0; i < ARRAY_SIZE(nvmet_transport); i++) {
 		if (sysfs_streq(page, nvmet_transport[i].name))
@@ -398,7 +403,8 @@ static ssize_t nvmet_addr_trtype_store(struct config_item *item,
 	}
 
 	pr_err("Invalid value '%s' for trtype\n", page);
-	return -EINVAL;
+	ret = -EINVAL;
+	goto out;
 
 found:
 	memset(&port->disc_addr.tsas, 0, NVMF_TSAS_SIZE);
@@ -407,7 +413,9 @@ static ssize_t nvmet_addr_trtype_store(struct config_item *item,
 		nvmet_port_init_tsas_rdma(port);
 	else if (port->disc_addr.trtype == NVMF_TRTYPE_TCP)
 		nvmet_port_init_tsas_tcp(port, NVMF_TCP_SECTYPE_NONE);
-	return count;
+out:
+	up_write(&nvmet_config_sem);
+	return ret;
 }
 
 CONFIGFS_ATTR(nvmet_, addr_trtype);
diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 07a74c2e1f58..5aaeeffc9ba2 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -393,11 +393,13 @@ void nvmet_disable_port(struct nvmet_port *port)
 
 	lockdep_assert_held(&nvmet_config_sem);
 
-	port->enabled = false;
-	port->tr_ops = NULL;
+	if (!port->enabled)
+		return;
 
-	ops = nvmet_transports[port->disc_addr.trtype];
+	ops = port->tr_ops;
+	port->enabled = false;
 	ops->remove_port(port);
+	port->tr_ops = NULL;
 	module_put(ops->owner);
 }
 

base-commit: 864c07de0c7dcbca58b61625dfa2e461ae63b242
-- 
2.39.5 (Apple Git-154)