Re: [RFC PATCH v1 16/16] vsock_test: SEQPACKET read to broken buffer

[Stefano Garzarella]

On Mon, Jun 28, 2021 at 01:05:36PM +0300, Arseny Krasnov wrote:
>Add test where sender sends two message, each with own
>data pattern. Reader tries to read first to broken buffer:
>it has three pages size, but middle page is unmapped. Then,
>reader tries to read second message to valid buffer. Test
>checks, that uncopied part of first message was dropped
>and thus not copied as part of second message.
>
>Signed-off-by: Arseny Krasnov <arseny.krasnov@xxxxxxxxxxxxx>
>---
> tools/testing/vsock/vsock_test.c | 121 +++++++++++++++++++++++++++++++
> 1 file changed, 121 insertions(+)

Cool test! Thanks for doing this!

>
>diff --git a/tools/testing/vsock/vsock_test.c b/tools/testing/vsock/vsock_test.c
>index 67766bfe176f..697ba168e97f 100644
>--- a/tools/testing/vsock/vsock_test.c
>+++ b/tools/testing/vsock/vsock_test.c
>@@ -16,6 +16,7 @@
> #include <linux/kernel.h>
> #include <sys/types.h>
> #include <sys/socket.h>
>+#include <sys/mman.h>
>
> #include "timeout.h"
> #include "control.h"
>@@ -385,6 +386,121 @@ static void test_seqpacket_msg_trunc_server(const struct test_opts *opts)
>       close(fd);
> }
>
>+#define BUF_PATTERN_1 'a'
>+#define BUF_PATTERN_2 'b'
>+
>+static void test_seqpacket_invalid_rec_buffer_client(const struct test_opts *opts)
>+{
>+      int fd;
>+      unsigned char *buf1;
>+      unsigned char *buf2;
>+      int buf_size = getpagesize() * 3;
>+
>+      fd = vsock_seqpacket_connect(opts->peer_cid, 1234);
>+      if (fd < 0) {
>+              perror("connect");
>+              exit(EXIT_FAILURE);
>+      }
>+
>+      buf1 = malloc(buf_size);
>+      if (buf1 == NULL) {

checkpatch suggests to use "if (!buf1)" ...

>+              perror("'malloc()' for 'buf1'");
>+              exit(EXIT_FAILURE);
>+      }
>+
>+      buf2 = malloc(buf_size);
>+      if (buf2 == NULL) {

... and "if (!buf2)" ...

>+              perror("'malloc()' for 'buf2'");
>+              exit(EXIT_FAILURE);
>+      }
>+
>+      memset(buf1, BUF_PATTERN_1, buf_size);
>+      memset(buf2, BUF_PATTERN_2, buf_size);
>+
>+      if (send(fd, buf1, buf_size, 0) != buf_size) {
>+              perror("send failed");
>+              exit(EXIT_FAILURE);
>+      }
>+
>+      if (send(fd, buf2, buf_size, 0) != buf_size) {
>+              perror("send failed");
>+              exit(EXIT_FAILURE);
>+      }
>+
>+      close(fd);
>+}
>+
>+static void test_seqpacket_invalid_rec_buffer_server(const struct test_opts *opts)
>+{
>+      int fd;
>+      unsigned char *broken_buf;
>+      unsigned char *valid_buf;
>+      int page_size = getpagesize();
>+      int buf_size = page_size * 3;
>+      ssize_t res;
>+      int prot = PROT_READ | PROT_WRITE;
>+      int flags = MAP_PRIVATE | MAP_ANONYMOUS;
>+      int i;
>+
>+      fd = vsock_seqpacket_accept(VMADDR_CID_ANY, 1234, NULL);
>+      if (fd < 0) {
>+              perror("accept");
>+              exit(EXIT_FAILURE);
>+      }
>+
>+      /* Setup first buffer. */
>+      broken_buf = mmap(NULL, buf_size, prot, flags, -1, 0);
>+      if (broken_buf == MAP_FAILED) {
>+              perror("mmap for 'broken_buf'");
>+              exit(EXIT_FAILURE);
>+      }
>+
>+      /* Unmap "hole" in buffer. */
>+      if (munmap(broken_buf + page_size, page_size)) {
>+              perror("'broken_buf' setup");
>+              exit(EXIT_FAILURE);
>+      }
>+
>+      valid_buf = mmap(NULL, buf_size, prot, flags, -1, 0);
>+      if (valid_buf == MAP_FAILED) {
>+              perror("mmap for 'valid_buf'");
>+              exit(EXIT_FAILURE);
>+      }
>+
>+      /* Try to fill buffer with unmapped middle. */
>+      res = read(fd, broken_buf, buf_size);
>+      if (res != -1) {
>+              perror("invalid read result of 'broken_buf'");
>+              exit(EXIT_FAILURE);
>+      }
>+
>+      if (errno != ENOMEM) {
>+              perror("invalid errno of 'broken_buf'");
>+              exit(EXIT_FAILURE);
>+      }
>+
>+      /* Try to fill valid buffer. */
>+      res = read(fd, valid_buf, buf_size);
>+      if (res != buf_size) {
>+              perror("invalid read result of 'valid_buf'");
>+              exit(EXIT_FAILURE);
>+      }
>+
>+      for (i = 0; i < buf_size; i++) {
>+              if (valid_buf[i] != BUF_PATTERN_2) {
>+                      perror("invalid pattern for valid buf");
>+                      exit(EXIT_FAILURE);
>+              }
>+      }
>+
>+

... and to remove the extra blank line here :-)

Thanks,
Stefano

>+      /* Unmap buffers. */
>+      munmap(broken_buf, page_size);
>+      munmap(broken_buf + page_size * 2, page_size);
>+      munmap(valid_buf, buf_size);
>+      close(fd);
>+}
>+
> static struct test_case test_cases[] = {
>       {
>               .name = "SOCK_STREAM connection reset",
>@@ -425,6 +541,11 @@ static struct test_case test_cases[] = {
>               .run_client = test_seqpacket_msg_trunc_client,
>               .run_server = test_seqpacket_msg_trunc_server,
>       },
>+      {
>+              .name = "SOCK_SEQPACKET invalid receive buffer",
>+              .run_client = test_seqpacket_invalid_rec_buffer_client,
>+              .run_server = test_seqpacket_invalid_rec_buffer_server,
>+      },
>       {},
> };
>
>--
>2.25.1
>