netdev - [PATCH net-next v3 5/7] vsock/test: Add test for accept

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Message-Id: <20241218-test-vsock-leaks-v3-5-f1a4dcef9228@rbox.co>
Date: Wed, 18 Dec 2024 15:32:38 +0100
From: Michal Luczaj <mhal@...x.co>
To: Stefano Garzarella <sgarzare@...hat.com>
Cc: netdev@...r.kernel.org, Michal Luczaj <mhal@...x.co>
Subject: [PATCH net-next v3 5/7] vsock/test: Add test for accept_queue
 memory leak

Attempt to enqueue a child after the queue was flushed, but before
SOCK_DONE flag has been set.

Test tries to produce a memory leak, kmemleak should be employed. Dealing
with a race condition, test by its very nature may lead to a false
negative.

Fixed by commit d7b0ff5a8667 ("virtio/vsock: Fix accept_queue memory
leak").

Signed-off-by: Michal Luczaj <mhal@...x.co>
---
 tools/testing/vsock/vsock_test.c | 52 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/tools/testing/vsock/vsock_test.c b/tools/testing/vsock/vsock_test.c
index 8bb2ab41c55f5c4d76e89903f80411915296c44e..2a8fcb062d9d207be988da5dd350e503ca20a143 100644
--- a/tools/testing/vsock/vsock_test.c
+++ b/tools/testing/vsock/vsock_test.c
@@ -29,6 +29,10 @@
 #include "control.h"
 #include "util.h"
 
+/* Basic messages for control_writeulong(), control_readulong() */
+#define CONTROL_CONTINUE	1
+#define CONTROL_DONE		0
+
 static void test_stream_connection_reset(const struct test_opts *opts)
 {
 	union {
@@ -1474,6 +1478,49 @@ static void test_stream_cred_upd_on_set_rcvlowat(const struct test_opts *opts)
 	test_stream_credit_update_test(opts, false);
 }
 
+/* The goal of test leak_acceptq is to stress the race between connect() and
+ * close(listener). Implementation of client/server loops boils down to:
+ *
+ * client                server
+ * ------                ------
+ * write(CONTINUE)
+ *                       expect(CONTINUE)
+ *                       listen()
+ *                       write(LISTENING)
+ * expect(LISTENING)
+ * connect()             close()
+ */
+#define ACCEPTQ_LEAK_RACE_TIMEOUT 2 /* seconds */
+
+static void test_stream_leak_acceptq_client(const struct test_opts *opts)
+{
+	time_t tout;
+	int fd;
+
+	tout = current_nsec() + ACCEPTQ_LEAK_RACE_TIMEOUT * NSEC_PER_SEC;
+	do {
+		control_writeulong(CONTROL_CONTINUE);
+
+		fd = vsock_stream_connect(opts->peer_cid, opts->peer_port);
+		if (fd >= 0)
+			close(fd);
+	} while (current_nsec() < tout);
+
+	control_writeulong(CONTROL_DONE);
+}
+
+/* Test for a memory leak. User is expected to run kmemleak scan, see README. */
+static void test_stream_leak_acceptq_server(const struct test_opts *opts)
+{
+	int fd;
+
+	while (control_readulong() == CONTROL_CONTINUE) {
+		fd = vsock_stream_listen(VMADDR_CID_ANY, opts->peer_port);
+		control_writeln("LISTENING");
+		close(fd);
+	}
+}
+
 static struct test_case test_cases[] = {
 	{
 		.name = "SOCK_STREAM connection reset",
@@ -1604,6 +1651,11 @@ static struct test_case test_cases[] = {
 		.run_client = test_seqpacket_unsent_bytes_client,
 		.run_server = test_seqpacket_unsent_bytes_server,
 	},
+	{
+		.name = "SOCK_STREAM leak accept queue",
+		.run_client = test_stream_leak_acceptq_client,
+		.run_server = test_stream_leak_acceptq_server,
+	},
 	{},
 };
 

-- 
2.47.1