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

[SJ Park <sj@kernel.org>]

'get_maintainer.pl --nogit --nogit-fallback' suggests adding below recipients.
I added them.

- Zi Yan <ziy@nvidia.com>
- Baolin Wang <baolin.wang@linux.alibaba.com>
- "Liam R. Howlett" <liam@infradead.org>
- Nico Pache <nico.pache@linux.dev>
- Ryan Roberts <ryan.roberts@arm.com>
- Dev Jain <dev.jain@arm.com>
- Barry Song <baohua@kernel.org>
- Lance Yang <lance.yang@linux.dev>
- Usama Arif <usama.arif@linux.dev>
- Vlastimil Babka <vbabka@kernel.org>
- Mike Rapoport <rppt@kernel.org>
- Suren Baghdasaryan <surenb@google.com>
- Michal Hocko <mhocko@suse.com>

On Wed, 19 Aug 2026 17:44:26 +0530 Anshuman <anshumantewari123@gmail.com> 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@gmail.com>

Reviewed-by: SJ Park <sj@kernel.org>


Thanks,
SJ

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