nvme-auth: don't override ctrl keys before validation

Replace ctrl ctrl_key/host_key only after nvme_auth_generate_key is successful.
Also, this fixes a bug where the keys are leaked.
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/core.c

@@ -3776,13 +3776,17 @@ static ssize_t nvme_ctrl_dhchap_secret_store(struct device *dev,
 	memcpy(dhchap_secret, buf, count);
 	nvme_auth_stop(ctrl);
 	if (strcmp(dhchap_secret, opts->dhchap_secret)) {
+		struct nvme_dhchap_key *key, *host_key;
 		int ret;
 
-		ret = nvme_auth_generate_key(dhchap_secret, &ctrl->host_key);
+		ret = nvme_auth_generate_key(dhchap_secret, &key);
 		if (ret)
 			return ret;
 		kfree(opts->dhchap_secret);
 		opts->dhchap_secret = dhchap_secret;
+		host_key = ctrl->host_key;
+		ctrl->host_key = key;
+		nvme_auth_free_key(host_key);
 		/* Key has changed; re-authentication with new key */
 		nvme_auth_reset(ctrl);
 	}
@@ -3826,13 +3830,17 @@ static ssize_t nvme_ctrl_dhchap_ctrl_secret_store(struct device *dev,
 	memcpy(dhchap_secret, buf, count);
 	nvme_auth_stop(ctrl);
 	if (strcmp(dhchap_secret, opts->dhchap_ctrl_secret)) {
+		struct nvme_dhchap_key *key, *ctrl_key;
 		int ret;
 
-		ret = nvme_auth_generate_key(dhchap_secret, &ctrl->ctrl_key);
+		ret = nvme_auth_generate_key(dhchap_secret, &key);
 		if (ret)
 			return ret;
 		kfree(opts->dhchap_ctrl_secret);
 		opts->dhchap_ctrl_secret = dhchap_secret;
+		ctrl_key = ctrl->ctrl_key;
+		ctrl->ctrl_key = key;
+		nvme_auth_free_key(ctrl_key);
 		/* Key has changed; re-authentication with new key */
 		nvme_auth_reset(ctrl);
 	}