Re: [RFC] enable UBSAN for automation tests

["Alejandro Vallejo" <alejandro.vallejo@cloud.com>]

On Wed Feb 5, 2025 at 12:44 AM GMT, Stefano Stabellini wrote:
> Hi all,
>
> I would like to propose to enable the UBSAN config option in our Gitlab
> pipelines. The attached patch (just for testing, do not commit) enables
> UBSAN on the Xen build jobs used for most of the ARM and x86 tests. The
> pipeline passes.
>
> https://gitlab.com/xen-project/people/sstabellini/xen/-/pipelines/1656001157
>
> Cheers,
>
> Stefano
>
> diff --git a/automation/gitlab-ci/build.yaml b/automation/gitlab-ci/build.yaml
> index bc4a8a5ad2..92790648aa 100644
> --- a/automation/gitlab-ci/build.yaml
> +++ b/automation/gitlab-ci/build.yaml
> @@ -333,6 +333,8 @@ alpine-3.18-gcc-debug:
>        CONFIG_EXPERT=y
>        CONFIG_UNSUPPORTED=y
>        CONFIG_ARGO=y
> +      CONFIG_UBSAN=y
> +      CONFIG_UBSAN_FATAL=y
>  
>  debian-12-x86_64-gcc-debug:
>    extends: .gcc-x86-64-build-debug
> @@ -419,6 +421,11 @@ alpine-3.18-gcc-debug-arm64:
>    extends: .gcc-arm64-build-debug
>    variables:
>      CONTAINER: alpine:3.18-arm64v8
> +    EXTRA_XEN_CONFIG: |
> +      CONFIG_EXPERT=y
> +      CONFIG_UNSUPPORTED=y
> +      CONFIG_UBSAN=y
> +      CONFIG_UBSAN_FATAL=y
>  
>  alpine-3.18-gcc-arm64-randconfig:
>    extends: .gcc-arm64-build

Sounds good to me. Particularly seeing how the pipeline is already clean. We
did some UBSAN checking in XenServer and it did uncovered a number of "oops,
yes that shouldn't quite be like that" sort of issues.

There's already precedent for making debug builds do slightly different things
to exercise different code paths (e.g: forcing map_domain_page() to always use
the mapcache rather than short-circuiting via the directmap).

Cheers,
Alejandro