02.04.2026 11:18, Luigi Leonardi wrote:
> Add a test that verifies MSG_PEEK works correctly after a partial
> recv().
>
> This is to test a bug that was present in the
> `virtio_transport_stream_do_peek()`
> when computing the number of bytes to copy: After a partial read, the
> peek function didn't take into consideration the number of bytes that
> were already read. So peeking the whole buffer would cause a out-of-bounds
> read,
> that resulted in a -EFAULT.
>
> This test does exactly this: do a partial recv on a buffer, then try to
> peek the whole buffer content.
>
> Signed-off-by: Luigi Leonardi <[email protected]>
> ---
> tools/testing/vsock/vsock_test.c | 64
> ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 64 insertions(+)
>
> diff --git a/tools/testing/vsock/vsock_test.c
> b/tools/testing/vsock/vsock_test.c
> index
> 5bd20ccd9335caafe68e8b7a5d02a4deb3d2deec..308f9f8f30d22bec5aaa282356e400d8438fe321
> 100644
> --- a/tools/testing/vsock/vsock_test.c
> +++ b/tools/testing/vsock/vsock_test.c
> @@ -346,6 +346,65 @@ static void test_stream_msg_peek_server(const struct
> test_opts *opts)
> return test_msg_peek_server(opts, false);
> }
>
> +#define PEEK_AFTER_RECV_LEN 100
Hi, may be we can just reuse MSG_PEEK_BUF_LEN which was already used in
MSG_PEEK tests ?
Thanks
> +
> +static void test_stream_peek_after_recv_client(const struct test_opts *opts)
> +{
> + unsigned char buf[PEEK_AFTER_RECV_LEN];
> + int fd;
> + int i;
> +
> + fd = vsock_stream_connect(opts->peer_cid, opts->peer_port);
> + if (fd < 0) {
> + perror("connect");
> + exit(EXIT_FAILURE);
> + }
> +
> + for (i = 0; i < sizeof(buf); i++)
> + buf[i] = (unsigned char)i;
> +
> + control_expectln("SRVREADY");
> +
> + send_buf(fd, buf, sizeof(buf), 0, sizeof(buf));
> +
> + close(fd);
> +}
> +
> +static void test_stream_peek_after_recv_server(const struct test_opts *opts)
> +{
> + unsigned char buf[PEEK_AFTER_RECV_LEN];
> + int half = PEEK_AFTER_RECV_LEN / 2;
> + ssize_t ret;
> + int fd;
> +
> + fd = vsock_stream_accept(VMADDR_CID_ANY, opts->peer_port, NULL);
> + if (fd < 0) {
> + perror("accept");
> + exit(EXIT_FAILURE);
> + }
> +
> + control_writeln("SRVREADY");
> +
> + /* Partial recv to advance offset within the skb */
> + recv_buf(fd, buf, half, 0, half);
> +
> + /* Try to peek more than what remains: should return only 'half'
> + * bytes. Note: we can't use recv_buf() because it loops until
> + * all requested bytes are returned.
> + */
> + ret = recv(fd, buf, sizeof(buf), MSG_PEEK);
> + if (ret < 0) {
> + perror("recv");
> + exit(EXIT_FAILURE);
> + } else if (ret != half) {
> + fprintf(stderr, "MSG_PEEK after partial recv returned %d
> (expected %d)\n",
> + ret, half);
> + exit(EXIT_FAILURE);
> + }
> +
> + close(fd);
> +}
> +
> #define SOCK_BUF_SIZE (2 * 1024 * 1024)
> #define SOCK_BUF_SIZE_SMALL (64 * 1024)
> #define MAX_MSG_PAGES 4
> @@ -2520,6 +2579,11 @@ static struct test_case test_cases[] = {
> .run_client = test_stream_tx_credit_bounds_client,
> .run_server = test_stream_tx_credit_bounds_server,
> },
> + {
> + .name = "SOCK_STREAM MSG_PEEK after partial recv",
> + .run_client = test_stream_peek_after_recv_client,
> + .run_server = test_stream_peek_after_recv_server,
> + },
> {},
> };
>
>
