netdev - [PATCH net-next 4/4] vsock/test: Add test for MSG

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Message-Id: <20241206-test-vsock-leaks-v1-4-c31e8c875797@rbox.co>
Date: Fri, 06 Dec 2024 19:34:54 +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 4/4] vsock/test: Add test for MSG_ZEROCOPY
 completion memory leak

Exercise the ENOMEM error path by attempting to hit net.core.optmem_max
limit on send().

Fixed by commit 60cf6206a1f5 ("virtio/vsock: Improve MSG_ZEROCOPY error
handling").

Signed-off-by: Michal Luczaj <mhal@...x.co>
---
 tools/testing/vsock/vsock_test.c | 66 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)

diff --git a/tools/testing/vsock/vsock_test.c b/tools/testing/vsock/vsock_test.c
index f92c62b25a25d35ae63a77a0122a194051719169..6973e681490b363e3b9cedcf195844ba56da6f1d 100644
--- a/tools/testing/vsock/vsock_test.c
+++ b/tools/testing/vsock/vsock_test.c
@@ -1552,6 +1552,67 @@ static void test_stream_msgzcopy_leak_errq_server(const struct test_opts *opts)
 	close(fd);
 }
 
+static void test_stream_msgzcopy_leak_zcskb_client(const struct test_opts *opts)
+{
+	char buf[1024] = { 0 };
+	ssize_t optmem_max;
+	int fd, res;
+	FILE *f;
+
+	f = fopen("/proc/sys/net/core/optmem_max", "r");
+	if (!f) {
+		perror("fopen(optmem_max)");
+		exit(EXIT_FAILURE);
+	}
+
+	if (fscanf(f, "%zd", &optmem_max) != 1 || optmem_max > ~0U / 2) {
+		fprintf(stderr, "fscanf(optmem_max) failed\n");
+		exit(EXIT_FAILURE);
+	}
+
+	fclose(f);
+
+	fd = vsock_stream_connect(opts->peer_cid, opts->peer_port);
+	if (fd < 0) {
+		perror("connect");
+		exit(EXIT_FAILURE);
+	}
+
+	enable_so_zerocopy_check(fd);
+
+	/* The idea is to fail virtio_transport_init_zcopy_skb() by hitting
+	 * core.sysctl_optmem_max (sysctl net.core.optmem_max) limit check in
+	 * sock_omalloc().
+	 */
+	optmem_max *= 2;
+	errno = 0;
+	do {
+		res = send(fd, buf, sizeof(buf), MSG_ZEROCOPY);
+		optmem_max -= res;
+	} while (res > 0 && optmem_max > 0);
+
+	if (errno != ENOMEM) {
+		fprintf(stderr, "expected ENOMEM on send()\n");
+		exit(EXIT_FAILURE);
+	}
+
+	close(fd);
+}
+
+static void test_stream_msgzcopy_leak_zcskb_server(const struct test_opts *opts)
+{
+	int fd;
+
+	fd = vsock_stream_accept(VMADDR_CID_ANY, opts->peer_port, NULL);
+	if (fd < 0) {
+		perror("accept");
+		exit(EXIT_FAILURE);
+	}
+
+	vsock_wait_remote_close(fd);
+	close(fd);
+}
+
 static struct test_case test_cases[] = {
 	{
 		.name = "SOCK_STREAM connection reset",
@@ -1692,6 +1753,11 @@ static struct test_case test_cases[] = {
 		.run_client = test_stream_msgzcopy_leak_errq_client,
 		.run_server = test_stream_msgzcopy_leak_errq_server,
 	},
+	{
+		.name = "SOCK_STREAM MSG_ZEROCOPY leak completion skb",
+		.run_client = test_stream_msgzcopy_leak_zcskb_client,
+		.run_server = test_stream_msgzcopy_leak_zcskb_server,
+	},
 	{},
 };
 

-- 
2.47.1