tee: amdtee: fix memory leak in amdtee_open_session()

On these error paths the "sess" variable isn't freed.  It's a refcounted
pointer so we need to call kref_put().  I re-arranged the code a bit so
the error case is always handled before the success case and the error
paths are indented two tabs.

Fixes: 757cc3e9 ("tee: add AMD-TEE driver")
Reviewed-by: Rijo Thomas <Rijo-john.Thomas@amd.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

drivers/tee/amdtee/core.c

@@ -212,6 +212,19 @@ static int copy_ta_binary(struct tee_context *ctx, void *ptr, void **ta,
 	return rc;
 }
 
+static void destroy_session(struct kref *ref)
+{
+	struct amdtee_session *sess = container_of(ref, struct amdtee_session,
+						   refcount);
+
+	/* Unload the TA from TEE */
+	handle_unload_ta(sess->ta_handle);
+	mutex_lock(&session_list_mutex);
+	list_del(&sess->list_node);
+	mutex_unlock(&session_list_mutex);
+	kfree(sess);
+}
+
 int amdtee_open_session(struct tee_context *ctx,
 			struct tee_ioctl_open_session_arg *arg,
 			struct tee_param *param)
@@ -236,14 +249,12 @@ int amdtee_open_session(struct tee_context *ctx,
 
 	/* Load the TA binary into TEE environment */
 	handle_load_ta(ta, ta_size, arg);
-	if (arg->ret == TEEC_SUCCESS) {
+	if (arg->ret != TEEC_SUCCESS)
+		goto out;
+
 	mutex_lock(&session_list_mutex);
 	sess = alloc_session(ctxdata, arg->session);
 	mutex_unlock(&session_list_mutex);
-	}
-
-	if (arg->ret != TEEC_SUCCESS)
-		goto out;
 
 	if (!sess) {
 		rc = -ENOMEM;
@@ -259,40 +270,29 @@ int amdtee_open_session(struct tee_context *ctx,
 
 	if (i >= TEE_NUM_SESSIONS) {
 		pr_err("reached maximum session count %d\n", TEE_NUM_SESSIONS);
+		kref_put(&sess->refcount, destroy_session);
 		rc = -ENOMEM;
 		goto out;
 	}
 
 	/* Open session with loaded TA */
 	handle_open_session(arg, &session_info, param);
-
-	if (arg->ret == TEEC_SUCCESS) {
-		sess->session_info[i] = session_info;
-		set_session_id(sess->ta_handle, i, &arg->session);
-	} else {
+	if (arg->ret != TEEC_SUCCESS) {
 		pr_err("open_session failed %d\n", arg->ret);
 		spin_lock(&sess->lock);
 		clear_bit(i, sess->sess_mask);
 		spin_unlock(&sess->lock);
+		kref_put(&sess->refcount, destroy_session);
+		goto out;
 	}
+
+	sess->session_info[i] = session_info;
+	set_session_id(sess->ta_handle, i, &arg->session);
 out:
 	free_pages((u64)ta, get_order(ta_size));
 	return rc;
 }
 
-static void destroy_session(struct kref *ref)
-{
-	struct amdtee_session *sess = container_of(ref, struct amdtee_session,
-						   refcount);
-
-	/* Unload the TA from TEE */
-	handle_unload_ta(sess->ta_handle);
-	mutex_lock(&session_list_mutex);
-	list_del(&sess->list_node);
-	mutex_unlock(&session_list_mutex);
-	kfree(sess);
-}
-
 int amdtee_close_session(struct tee_context *ctx, u32 session)
 {
 	struct amdtee_context_data *ctxdata = ctx->data;