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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko Subject: Re: [PATCH] selftests/mm: check stat() return value in khugepaged get_finfo() Date: Wed, 19 Aug 2026 17:13:55 -0700 Message-ID: <20260820001356.87221-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260819121426.49500-1-anshumantewari123@gmail.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 3444A40005 X-Stat-Signature: 6f14chf96ienuapo9mdxzrkt5fc54oqy X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1787184848-554119 X-HE-Meta: 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 gM8L4hOK 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 'get_maintainer.pl --nogit --nogit-fallback' suggests adding below recipients. I added them. - Zi Yan - Baolin Wang - "Liam R. Howlett" - Nico Pache - Ryan Roberts - Dev Jain - Barry Song - Lance Yang - Usama Arif - Vlastimil Babka - Mike Rapoport - Suren Baghdasaryan - Michal Hocko On Wed, 19 Aug 2026 17:44:26 +0530 Anshuman 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 Reviewed-by: SJ Park Thanks, SJ [...]