queue-7.0/net-qrtr-ns-limit-the-maximum-server-registration-per-node.patch

From d5ee2ff98322337951c56398e79d51815acbf955 Mon Sep 17 00:00:00 2001
From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Date: Thu, 9 Apr 2026 23:04:12 +0530
Subject: net: qrtr: ns: Limit the maximum server registration per node

From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

commit d5ee2ff98322337951c56398e79d51815acbf955 upstream.

Current code does no bound checking on the number of servers added per
node. A malicious client can flood NEW_SERVER messages and exhaust memory.

Fix this issue by limiting the maximum number of server registrations to
256 per node. If the NEW_SERVER message is received for an old port, then
don't restrict it as it will get replaced. While at it, also rate limit
the error messages in the failure path of qrtr_ns_worker().

Note that the limit of 256 is chosen based on the current platform
requirements. If requirement changes in the future, this limit can be
increased.

Cc: stable@vger.kernel.org
Fixes: 0c2204a4ad71 ("net: qrtr: Migrate nameservice to kernel from userspace")
Reported-by: Yiming Qian <yimingqian591@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Link: https://patch.msgid.link/20260409-qrtr-fix-v3-1-00a8a5ff2b51@oss.qualcomm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/qrtr/ns.c |   26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

--- a/net/qrtr/ns.c
+++ b/net/qrtr/ns.c
@@ -68,8 +68,14 @@ struct qrtr_server {
 struct qrtr_node {
 	unsigned int id;
 	struct xarray servers;
+	u32 server_count;
 };
 
+/* Max server limit is chosen based on the current platform requirements. If the
+ * requirement changes in the future, this value can be increased.
+ */
+#define QRTR_NS_MAX_SERVERS 256
+
 static struct qrtr_node *node_get(unsigned int node_id)
 {
 	struct qrtr_node *node;
@@ -230,6 +236,17 @@ static struct qrtr_server *server_add(un
 	if (!service || !port)
 		return NULL;
 
+	node = node_get(node_id);
+	if (!node)
+		return NULL;
+
+	/* Make sure the new servers per port are capped at the maximum value */
+	old = xa_load(&node->servers, port);
+	if (!old && node->server_count >= QRTR_NS_MAX_SERVERS) {
+		pr_err_ratelimited("QRTR client node %u exceeds max server limit!\n", node_id);
+		return NULL;
+	}
+
 	srv = kzalloc_obj(*srv);
 	if (!srv)
 		return NULL;
@@ -239,10 +256,6 @@ static struct qrtr_server *server_add(un
 	srv->node = node_id;
 	srv->port = port;
 
-	node = node_get(node_id);
-	if (!node)
-		goto err;
-
 	/* Delete the old server on the same port */
 	old = xa_store(&node->servers, port, srv, GFP_KERNEL);
 	if (old) {
@@ -253,6 +266,8 @@ static struct qrtr_server *server_add(un
 		} else {
 			kfree(old);
 		}
+	} else {
+		node->server_count++;
 	}
 
 	trace_qrtr_ns_server_add(srv->service, srv->instance,
@@ -293,6 +308,7 @@ static int server_del(struct qrtr_node *
 	}
 
 	kfree(srv);
+	node->server_count--;
 
 	return 0;
 }
@@ -671,7 +687,7 @@ static void qrtr_ns_worker(struct work_s
 		}
 
 		if (ret < 0)
-			pr_err("failed while handling packet from %d:%d",
+			pr_err_ratelimited("failed while handling packet from %d:%d",
 			       sq.sq_node, sq.sq_port);
 	}