Re: [edk2-devel] [PATCH 0/3] MdePkg, OvmfPkg: rewrite Base64Decode(), clean up call site

["Laszlo Ersek" <lersek@redhat.com>]

On 07/02/19 12:28, Laszlo Ersek wrote:
> Repo:   https://github.com/lersek/edk2.git
> Branch: base64_decode_bz1891
>
> Base64Decode() has a number of issues; see
>
> - <https://bugzilla.tianocore.org/show_bug.cgi?id=1891>
>
> - and the mailing list discussion linked from
>   <https://bugzilla.tianocore.org/show_bug.cgi?id=1891#c6>.
>
> In my opinion, rewriting Base64Decode() from scratch, using a different
> (state machine-based) approach is safer / more robust than attempting to
> identify and patch up individual problems in the current implementation.
> The emphasis of the proposed implementation is to reject invalid input;
> decoding valid input is kind of secondary. (This is the safe approach
> for all parsers that process untrusted input, in my opinion.)
>
> My understanding is that unit tests for Base64Decode() already exist in
> some repository. While I tested the new implementation through OvmfPkg's
> EnrollDefaultKeys application -- which makes the sole calls to
> Base64Decode() in the open source edk2 tree -- I didn't run a unit test
> suite. Help with that (pointers to the test suite, or actual unit
> testing) would be highly appreciated.
>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Cc: Liming Gao <liming.gao@intel.com>
> Cc: Marvin Häuser <mhaeuser@outlook.de>
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
> Cc: Zhichao Gao <zhichao.gao@intel.com>
>
> Thanks
> Laszlo
>
> Laszlo Ersek (3):
>   MdePkg/BaseLib: re-specify Base64Decode(), and add temporary stub impl
>   MdePkg/BaseLib: rewrite Base64Decode()
>   OvmfPkg/EnrollDefaultKeys: clean up Base64Decode() retval handling
>
>  MdePkg/Include/Library/BaseLib.h              |  99 ++++-
>  MdePkg/Library/BaseLib/String.c               | 448 +++++++++++++-------
>  OvmfPkg/EnrollDefaultKeys/EnrollDefaultKeys.c |  10 +-
>  3 files changed, 374 insertions(+), 183 deletions(-)
>

Thank you all for the feedback!

* Added a paragraph to the commit message of patch#2, as requested by
  Phil, based on the discussion with Marvin:

    +    The intent is to only strengthen the checks (sanity and input) relative to
    +    the previous implementation, hence the MAX_ADDRESS checks are reinstated.
...
    +    [lersek@redhat.com: add last para to commit msg per talks w/ Marvin & Phil]

* Pushed the first two patches in the series as commit range
  84a459472075..35e242b698cd; closing
  <https://bugzilla.tianocore.org/show_bug.cgi?id=1891>.

* Filed <https://bugzilla.tianocore.org/show_bug.cgi?id=1980> to track
  the CCS non-conformance issue, under approach "2a" (i.e.,
  incrementally), as agreed upon with Zhichao. Assigned the BZ to
  myself; will post a patch soon.

* Split off the last patch in the series to a separate TianoCore BZ,
  namely <https://bugzilla.tianocore.org/show_bug.cgi?id=1981>. Assigned
  that BZ to myself too.

Thanks,
Laszlo