Re: [PATCH] selftests/mm: check stat() return value in khugepaged get_finfo()

[Anshuman Tewari]

Thanks for the review, SJ — and for the extra maintainer list from
--nogit-fallback, good to know for next time.

Anshuman


On Thu, 20 Aug 2026 at 05:44, SJ Park <sj@xxxxxxxxxx> wrote:
>
> 'get_maintainer.pl --nogit --nogit-fallback' suggests adding below recipients.
> I added them.
>
> - Zi Yan <ziy@xxxxxxxxxx>
> - Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
> - "Liam R. Howlett" <liam@xxxxxxxxxxxxx>
> - Nico Pache <nico.pache@xxxxxxxxx>
> - Ryan Roberts <ryan.roberts@xxxxxxx>
> - Dev Jain <dev.jain@xxxxxxx>
> - Barry Song <baohua@xxxxxxxxxx>
> - Lance Yang <lance.yang@xxxxxxxxx>
> - Usama Arif <usama.arif@xxxxxxxxx>
> - Vlastimil Babka <vbabka@xxxxxxxxxx>
> - Mike Rapoport <rppt@xxxxxxxxxx>
> - Suren Baghdasaryan <surenb@xxxxxxxxxx>
> - Michal Hocko <mhocko@xxxxxxxx>
>
> On Wed, 19 Aug 2026 17:44:26 +0530 Anshuman <anshumantewari123@xxxxxxxxx> wrote:
>
> > get_finfo() calls stat() to get metadata about the target directory,
> > but never checks the return value. On failure, stat() returns -1 and
> > leaves path_stat unmodified, so path_stat.st_mode may contain
> > uninitialized stack data.
> >
> > The code then checks S_ISDIR(path_stat.st_mode) against this
> > potentially garbage value. This can produce a misleading "Not a
> > directory" error when the real problem is a nonexistent or
> > inaccessible path, or, in the worst case, the check could pass by
> > chance on garbage data and let the function continue using an
> > invalid path_stat for the rest of its logic.
> >
> > Check the return value and fail with a clear error message if
> > stat() fails, matching the error-handling style already used for
> > statfs() and read_file() later in the same function.
>
> Makes sense to me.
>
> >
> > Signed-off-by: Anshuman <anshumantewari123@xxxxxxxxx>
>
> Reviewed-by: SJ Park <sj@xxxxxxxxxx>
>
>
> Thanks,
> SJ
>
> [...]