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").

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Link: https://patch.msgid.link/20241219-test-vsock-leaks-v4-5-a416e554d9d7@rbox.co
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/tools/testing/vsock/vsock_test.c b/tools/testing/vsock/vsock_test.c
index 8bb2ab41c55f5c4d76e89903f80411915296c44e..2a8fcb062d9d207be988da5dd350e503ca20a143 100644 (file)
--- 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,
+       },
        {},
 };