Re: [PATCH bpf v3 1/3] bpf: update local storage test to check handling of null ptrs

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Mon, Jan 11, 2021 at 11:55 PM KP Singh <kpsingh@kernel.org> wrote:
>
> It was found in [1] that bpf_inode_storage_get helper did not check
> the nullness of the passed owner ptr which caused an oops when
> dereferenced. This change incorporates the example suggested in [1] into
> the local storage selftest.
>
> The test is updated to create a temporary directory instead of just
> using a tempfile. In order to replicate the issue this copied rm binary
> is renamed tiggering the inode_rename with a null pointer for the
> new_inode. The logic to verify the setting and deletion of the inode
> local storage of the old inode is also moved to this LSM hook.
>
> The change also removes the copy_rm function and simply shells out
> to copy files and recursively delete directories and consolidates the
> logic of setting the initial inode storage to the bprm_committed_creds
> hook and removes the file_open hook.
>
> [1]: https://lore.kernel.org/bpf/CANaYP3HWkH91SN=wTNO9FL_2ztHfqcXKX38SSE-JJ2voh+vssw@mail.gmail.com
>
> Suggested-by: Gilad Reti <gilad.reti@gmail.com>
> Acked-by: Yonghong Song <yhs@fb.com>
> Signed-off-by: KP Singh <kpsingh@kernel.org>
> ---

Hi KP,

I'm getting a compilation warning when building selftests. Can you
please take a look and send a fix? Thanks!

/data/users/andriin/linux/tools/testing/selftests/bpf/prog_tests/test_local_storage.c:
In function ‘test_test_local_storage’:
/data/users/andriin/linux/tools/testing/selftests/bpf/prog_tests/test_local_storage.c:143:52:
warning: ‘/copy_of_rm’ directive output may be truncated writing 11
bytes into a region of size between 1 and 64 [-Wformat-truncation=]
  143 |  snprintf(tmp_exec_path, sizeof(tmp_exec_path), "%s/copy_of_rm",
      |                                                    ^~~~~~~~~~~
/data/users/andriin/linux/tools/testing/selftests/bpf/prog_tests/test_local_storage.c:143:2:
note: ‘snprintf’ output between 12 and 75 bytes into a destination of
size 64
  143 |  snprintf(tmp_exec_path, sizeof(tmp_exec_path), "%s/copy_of_rm",
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  144 |    tmp_dir_path);
      |    ~~~~~~~~~~~~~


>  .../bpf/prog_tests/test_local_storage.c       | 96 +++++--------------
>  .../selftests/bpf/progs/local_storage.c       | 62 ++++++------
>  2 files changed, 61 insertions(+), 97 deletions(-)
>

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