[RFC PATCH v1 1/3] test/vsock: SOCK_SEQPACKET 'rx_bytes'/'fwd_cnt' bug reproducer

[Arseniy Krasnov <avkrasnov@sberdevices.ru>]

virtio/vsock: replace virtio_vsock_pkt with sk_buff

Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
---
 net/vmw_vsock/virtio_transport_common.c |  4 +++
 tools/testing/vsock/vsock_test.c        | 44 +++++++++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index a1581c77cf84..77bb1cad8471 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -256,6 +256,10 @@ static void virtio_transport_dec_rx_pkt(struct virtio_vsock_sock *vvs,
 	int len;
 
 	len = skb_headroom(skb) - sizeof(struct virtio_vsock_hdr) - skb->len;
+
+	if (len < 0)
+		pr_emerg("Negative len %i\n", len);
+
 	vvs->rx_bytes -= len;
 	vvs->fwd_cnt += len;
 }
diff --git a/tools/testing/vsock/vsock_test.c b/tools/testing/vsock/vsock_test.c
index 67e9f9df3a8c..2651de2aedc9 100644
--- a/tools/testing/vsock/vsock_test.c
+++ b/tools/testing/vsock/vsock_test.c
@@ -860,7 +860,51 @@ static void test_stream_poll_rcvlowat_client(const struct test_opts *opts)
 	close(fd);
 }
 
+static void test_seqpacket_rxbytes_client(const struct test_opts *opts)
+{
+	unsigned char data[256];
+	int fd;
+
+	fd = vsock_seqpacket_connect(opts->peer_cid, 1234);
+	if (fd < 0) {
+		perror("connect");
+		exit(EXIT_FAILURE);
+	}
+
+	send(fd, data, sizeof(data), 0);
+
+	control_writeln("CLISENT");
+
+	close(fd);
+
+	exit(0);
+}
+
+static void test_seqpacket_rxbytes_server(const struct test_opts *opts)
+{
+	unsigned char data[8];
+	int fd;
+
+	fd = vsock_seqpacket_accept(VMADDR_CID_ANY, 1234, NULL);
+	if (fd < 0) {
+		perror("accept");
+		exit(EXIT_FAILURE);
+	}
+
+	control_expectln("CLISENT");
+	read(fd, data, sizeof(data));
+
+	close(fd);
+
+	exit(0);
+}
+
 static struct test_case test_cases[] = {
+	{
+		.name = "SOCK_SEQPACKET negative 'rx_bytes'",
+		.run_client = test_seqpacket_rxbytes_client,
+		.run_server = test_seqpacket_rxbytes_server,
+	},
 	{
 		.name = "SOCK_STREAM connection reset",
 		.run_client = test_stream_connection_reset,
-- 
2.25.1