[PATCH] nvmet: Check the admin queue before reading its TLS key in debugfs

[Guixin Liu <kanie@linux.alibaba.com>]

nvmet_ctrl_tls_key_show() dereferences ctrl->sqs[0] unconditionally,
but the admin queue is not installed yet while the controller is
being created, and sqs[0] is set to NULL again when it is destroyed.
Reading the tls_key debugfs entry in either window crashes the kernel.

Only query the queue's TLS key when the admin queue is present and
report 0 otherwise.

Fixes: 316dabe6089fe ("nvmet: add tls_concat and tls_key debugfs entries")
Cc: stable@vger.kernel.org
Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
---
 drivers/nvme/target/debugfs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/target/debugfs.c b/drivers/nvme/target/debugfs.c
index e85fe1d4c9f8..a27a501fe61a 100644
--- a/drivers/nvme/target/debugfs.c
+++ b/drivers/nvme/target/debugfs.c
@@ -136,8 +136,10 @@ NVMET_DEBUGFS_ATTR(nvmet_ctrl_host_traddr);
 static int nvmet_ctrl_tls_key_show(struct seq_file *m, void *p)
 {
 	struct nvmet_ctrl *ctrl = m->private;
-	key_serial_t keyid = nvmet_queue_tls_keyid(ctrl->sqs[0]);
+	key_serial_t keyid = 0;
 
+	if (ctrl->sqs[0])
+		keyid = nvmet_queue_tls_keyid(ctrl->sqs[0]);
 	seq_printf(m, "%08x\n", keyid);
 	return 0;
 }
-- 
2.43.7