From: Sasha Levin <sashal@kernel.org>
To: stable@vger.kernel.org
Cc: Chuck Lever <chuck.lever@oracle.com>,
	Jeff Layton <jlayton@kernel.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10.y 4/4] svcrdma: Reject connection when transport allocation fails
Date: Tue,  8 Sep 2026 21:37:27 -0400
Message-ID: <20260909013727.906528-4-sashal@kernel.org>
In-Reply-To: <20260909013727.906528-1-sashal@kernel.org>
References: <2026090304-champion-prevent-c92a@gregkh>
 <20260909013727.906528-1-sashal@kernel.org>
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From: Chuck Lever <chuck.lever@oracle.com>

[ Upstream commit 0944462247dcb7de7622cdaaadf5f05c52707dab ]

handle_connect_req() returns without action when
svc_rdma_create_xprt() fails to allocate the new transport.
The CM core returns 0 for CONNECT_REQUEST events, so it does
not destroy the new rdma_cm_id. Each allocation failure under
memory pressure leaks one rdma_cm_id, and a remote peer driving
connection attempts can amplify this.

Reject the connection by returning a non-zero status from the
CM event handler, which tells the CM core to destroy the
orphaned cm_id.

Fixes: 377f9b2f4529 ("rdma: SVCRDMA Core Transport Services")
Cc: stable@vger.kernel.org
Acked-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260527-rdma-follow-on-v1-4-1b09bd87b6cd@oracle.com
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/sunrpc/xprtrdma/svc_rdma_transport.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index 9adb2ad031e97..38843fd6f35fd 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -223,12 +223,16 @@ svc_rdma_parse_connect_private(struct svcxprt_rdma *newxprt,
  * structure for the listening endpoint.
  *
  * This function creates a new xprt for the new connection and enqueues it on
- * the accept queue for the listent xprt. When the listen thread is kicked, it
+ * the accept queue for the listen xprt. When the listen thread is kicked, it
  * will call the recvfrom method on the listen xprt which will accept the new
  * connection.
+ *
+ * Return values:
+ *     %0: Do not destroy @new_cma_id
+ *     %1: Destroy @new_cma_id (allocation failure)
  */
-static void handle_connect_req(struct rdma_cm_id *new_cma_id,
-			       struct rdma_conn_param *param)
+static int handle_connect_req(struct rdma_cm_id *new_cma_id,
+			      struct rdma_conn_param *param)
 {
 	struct svcxprt_rdma *listen_xprt = new_cma_id->context;
 	struct svcxprt_rdma *newxprt;
@@ -238,7 +242,7 @@ static void handle_connect_req(struct rdma_cm_id *new_cma_id,
 				       listen_xprt->sc_xprt.xpt_net,
 				       ibdev_to_node(new_cma_id->device));
 	if (!newxprt)
-		return;
+		return 1;
 	newxprt->sc_cm_id = new_cma_id;
 	new_cma_id->context = newxprt;
 	svc_rdma_parse_connect_private(newxprt, param);
@@ -272,6 +276,7 @@ static void handle_connect_req(struct rdma_cm_id *new_cma_id,
 
 	set_bit(XPT_CONN, &listen_xprt->sc_xprt.xpt_flags);
 	svc_xprt_enqueue(&listen_xprt->sc_xprt);
+	return 0;
 }
 
 /**
@@ -295,8 +300,7 @@ static int svc_rdma_listen_handler(struct rdma_cm_id *cma_id,
 
 	switch (event->event) {
 	case RDMA_CM_EVENT_CONNECT_REQUEST:
-		handle_connect_req(cma_id, &event->param.conn);
-		break;
+		return handle_connect_req(cma_id, &event->param.conn);
 	case RDMA_CM_EVENT_ADDR_CHANGE:
 		listen_id = svc_rdma_create_listen_id(cma_rdma->xpt_net,
 						      sap, cma_xprt);
-- 
2.53.0