Re: [PATCH v7 4/4] selftests/liveupdate: add test cases for LIVEUPDATE_SESSION_GET_NAME

Pasha Tatashin
2026-04-18T15:50:30Z

On 04-18 15:09, luca.boccassi@gmail.com wrote:
> From: Luca Boccassi <luca.boccassi@gmail.com>
>
> Verify that the new LIVEUPDATE_SESSION_GET_NAME ioctl works
> as expected via new test cases in the existing liveupdate selftest.
>
> Signed-off-by: Luca Boccassi <luca.boccassi@gmail.com>
> ---
> v5: merge with LUO_SESSION_MAGIC series as they both change the same
> unit test file, to avoid merge conflicts
> split into separate patch
> v6: add more test cases as suggested
> more verbose commit message
>
> .../testing/selftests/liveupdate/liveupdate.c | 138 ++++++++++++++++++
> 1 file changed, 138 insertions(+)
>
> diff --git a/tools/testing/selftests/liveupdate/liveupdate.c b/tools/testing/selftests/liveupdate/liveupdate.c
> index d132b4685f76..ffbcbd465c9b 100644
> --- a/tools/testing/selftests/liveupdate/liveupdate.c
> +++ b/tools/testing/selftests/liveupdate/liveupdate.c
> @@ -105,6 +105,22 @@ static int create_session(int lu_fd, const char *name)
> return args.fd;
> }
>
> +/* Helper function to get a session name via ioctl. */
> +static int get_session_name(int session_fd, char *name, size_t name_len)
> +{
> + struct liveupdate_session_get_name args = {};
> +
> + args.size = sizeof(args);
> +
> + if (ioctl(session_fd, LIVEUPDATE_SESSION_GET_NAME, &args))
> + return -errno;
> +
> + strncpy(name, (char *)args.name, name_len - 1);
> + name[name_len - 1] = '\0';
> +
> + return 0;
> +}
> +
> /*
> * Test Case: Create Duplicate Session
> *
> @@ -385,4 +401,126 @@ TEST_F(liveupdate_device, session_fstat)
> ASSERT_EQ(close(session_fd2), 0);
> }
>
> +/*
> + * Test Case: Get Session Name
> + *
> + * Verifies that the full session name can be retrieved from a session file
> + * descriptor via ioctl.
> + */
> +TEST_F(liveupdate_device, get_session_name)
> +{
> + char name_buf[LIVEUPDATE_SESSION_NAME_LENGTH] = {};
> + const char *session_name = "get-name-test-session";
> + int session_fd;
> +
> + self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
> + if (self->fd1 < 0 && errno == ENOENT)
> + SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
> + ASSERT_GE(self->fd1, 0);
> +
> + session_fd = create_session(self->fd1, session_name);
> + ASSERT_GE(session_fd, 0);
> +
> + ASSERT_EQ(get_session_name(session_fd, name_buf, sizeof(name_buf)), 0);
> + ASSERT_STREQ(name_buf, session_name);
> +
> + ASSERT_EQ(close(session_fd), 0);
> +}
> +
> +/*
> + * Test Case: Get Session Name at Maximum Length
> + *
> + * Verifies that a session name using the full LIVEUPDATE_SESSION_NAME_LENGTH
> + * (minus the null terminator) can be correctly retrieved.
> + */
> +TEST_F(liveupdate_device, get_session_name_max_length)
> +{
> + char name_buf[LIVEUPDATE_SESSION_NAME_LENGTH] = {};
> + char long_name[LIVEUPDATE_SESSION_NAME_LENGTH];
> + int session_fd;
> +
> + memset(long_name, 'A', sizeof(long_name) - 1);
> + long_name[sizeof(long_name) - 1] = '\0';
> +
> + self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
> + if (self->fd1 < 0 && errno == ENOENT)
> + SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
> + ASSERT_GE(self->fd1, 0);
> +
> + session_fd = create_session(self->fd1, long_name);
> + ASSERT_GE(session_fd, 0);
> +
> + ASSERT_EQ(get_session_name(session_fd, name_buf, sizeof(name_buf)), 0);
> + ASSERT_STREQ(name_buf, long_name);
> +
> + ASSERT_EQ(close(session_fd), 0);
> +}
> +
> +/*
> + * Test Case: Create Session with No Null Termination
> + *
> + * Verifies that filling the entire 64-byte name field with non-null characters
> + * (no '\0' terminator) is handled safely by the kernel. The kernel's strscpy
> + * truncates to 63 characters, which we verify via get_session_name.

[...]

> + */
> +TEST_F(liveupdate_device, create_session_no_null_termination)
> +{
> + struct liveupdate_ioctl_create_session args = {};
> + char expected_name[LIVEUPDATE_SESSION_NAME_LENGTH];
> + char name_buf[LIVEUPDATE_SESSION_NAME_LENGTH] = {};
> + int session_fd;
> +
> + self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
> + if (self->fd1 < 0 && errno == ENOENT)
> + SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
> + ASSERT_GE(self->fd1, 0);
> +
> + /* Fill entire name field with 'X', no null terminator */
> + args.size = sizeof(args);
> + memset(args.name, 'X', sizeof(args.name));
> +
> + ASSERT_EQ(ioctl(self->fd1, LIVEUPDATE_IOCTL_CREATE_SESSION, &args), 0);
> + session_fd = args.fd;
> + ASSERT_GE(session_fd, 0);
> +
> + /* Kernel should have truncated to 63 chars + '\0' */
> + memset(expected_name, 'X', sizeof(expected_name) - 1);
> + expected_name[sizeof(expected_name) - 1] = '\0';
> +
> + ASSERT_EQ(get_session_name(session_fd, name_buf, sizeof(name_buf)), 0);
> + ASSERT_STREQ(name_buf, expected_name);
> +
> + ASSERT_EQ(close(session_fd), 0);
> +}
> +
> +/*
> + * Test Case: Create Session with Empty Name
> + *
> + * Verifies that creating a session with an empty string name succeeds,
> + * and that creating a second session with the same empty name fails
> + * with EEXIST.
> + */

For the two cases mentioned above, we should implement a fix in the
kernel:

In luo_session_create(), we should verify that the name is at least 1
character long and at most LIVEUPDATE_SESSION_NAME_LENGTH - 1.

size_t len = strnlen(name, LIVEUPDATE_SESSION_NAME_LENGTH);

if (!len || len > LIVEUPDATE_SESSION_NAME_LENGTH - 1)
return -EINVAL;

This change should be submitted as a separate patch in your series.

Additionally, please include a cover letter in the next version
explaining the overall series. Once the cover letter is included, you
can remove the individual patch versions from the stat areas.

Pasha