From a0f46809c5cef87f83c1e3f57429f77a6b443adb Mon Sep 17 00:00:00 2001
From: Chris Lew <quic_clew@quicinc.com>
Date: Mon, 3 Oct 2022 09:57:02 -0700
Subject: [PATCH] net: qrtr: Do not send packets before hello negotiation

There is a race where broadcast packets can be sent to a node that has
not sent the hello message to the remote processor. This breaks the
protocol expectation. Add a status variable to track when the hello
packet has been sent.

An alternative solution attempted was to remove the nodes from the
broadcast list until the hello packet is sent. This is not a valid
solution because hello messages are broadcasted if the ns is restarted
or started late. There needs to be a status variable separate from the
broadcast list.

Change-Id: I2a55e587f324e64e2bde4ea634de66008f190de1
Signed-off-by: Chris Lew <quic_clew@quicinc.com>
---
 net/qrtr/af_qrtr.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/net/qrtr/af_qrtr.c b/net/qrtr/af_qrtr.c
index 5c2fb992803b..b502ccd6377f 100644
--- a/net/qrtr/af_qrtr.c
+++ b/net/qrtr/af_qrtr.c
@@ -2,6 +2,7 @@
 /*
  * Copyright (c) 2015, Sony Mobile Communications Inc.
  * Copyright (c) 2013, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
  */
 #include <linux/module.h>
 #include <linux/netlink.h>
@@ -118,6 +119,7 @@ static DEFINE_XARRAY_ALLOC(qrtr_ports);
  * @nid: node id
  * @qrtr_tx_flow: tree of qrtr_tx_flow, keyed by node << 32 | port
  * @qrtr_tx_lock: lock for qrtr_tx_flow inserts
+ * @hello_sent: hello packet sent to endpoint
  * @rx_queue: receive queue
  * @item: list item for broadcast list
  */
@@ -126,6 +128,7 @@ struct qrtr_node {
 	struct qrtr_endpoint *ep;
 	struct kref ref;
 	unsigned int nid;
+	atomic_t hello_sent;
 
 	struct radix_tree_root qrtr_tx_flow;
 	struct mutex qrtr_tx_lock; /* for qrtr_tx_flow */
@@ -343,6 +346,11 @@ static int qrtr_node_enqueue(struct qrtr_node *node, struct sk_buff *skb,
 	size_t len = skb->len;
 	int rc, confirm_rx;
 
+	if (!atomic_read(&node->hello_sent) && type != QRTR_TYPE_HELLO) {
+		kfree_skb(skb);
+		return 0;
+	}
+
 	confirm_rx = qrtr_tx_wait(node, to->sq_node, to->sq_port, type);
 	if (confirm_rx < 0) {
 		kfree_skb(skb);
@@ -380,6 +388,8 @@ static int qrtr_node_enqueue(struct qrtr_node *node, struct sk_buff *skb,
 	 * confirm_rx flag if we dropped this one */
 	if (rc && confirm_rx)
 		qrtr_tx_flow_failed(node, to->sq_node, to->sq_port);
+	if (!rc && type == QRTR_TYPE_HELLO)
+		atomic_inc(&node->hello_sent);
 
 	return rc;
 }
@@ -589,6 +599,7 @@ int qrtr_endpoint_register(struct qrtr_endpoint *ep, unsigned int nid)
 	skb_queue_head_init(&node->rx_queue);
 	node->nid = QRTR_EP_NID_AUTO;
 	node->ep = ep;
+	atomic_set(&node->hello_sent, 0);
 
 	INIT_RADIX_TREE(&node->qrtr_tx_flow, GFP_KERNEL);
 	mutex_init(&node->qrtr_tx_lock);
@@ -875,6 +886,8 @@ static int qrtr_bcast_enqueue(struct qrtr_node *node, struct sk_buff *skb,
 
 	mutex_lock(&qrtr_node_lock);
 	list_for_each_entry(node, &qrtr_all_nodes, item) {
+		if (node->nid == QRTR_EP_NID_AUTO)
+			continue;
 		skbn = skb_clone(skb, GFP_KERNEL);
 		if (!skbn)
 			break;