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From: Muchun Song In-Reply-To: <20230323151850.e2785b1cff37fba078f26f2b@linux-foundation.org> Date: Fri, 24 Mar 2023 09:59:16 +0800 Cc: Muchun Song , glider@google.com, elver@google.com, dvyukov@google.com, jannh@google.com, sjpark@amazon.de, kasan-dev@googlegroups.com, Linux Memory Management List , linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: References: <20230323025003.94447-1-songmuchun@bytedance.com> <20230323151850.e2785b1cff37fba078f26f2b@linux-foundation.org> To: Andrew Morton X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C59BFA000E X-Stat-Signature: 36yfykep473gsarfd9iqh8d73a8pf4qk X-HE-Tag: 1679623194-651736 X-HE-Meta: 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 swdeKWvS vIJh35UrD+1AY+5XcI3rVrx4JoVIOSFuKhMfEnUuRKDKr25FTyBXqJR1jwDH86ryDg8zkxZn+mMSXgDrldwCgd5IER3VF/hNjT/CXD5K6bLV1CbGipgrjq8W1uh319egu2+M1mL4dj3O2efxv7+mPs58v816E+191m42TRArWp2ee1Nz0t5FwMpBc0TBOyVlsN+EFC/XAPFFmWwDVjK5OoP0WbVsPvja2MaaB X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > On Mar 24, 2023, at 06:18, Andrew Morton = wrote: >=20 > On Thu, 23 Mar 2023 10:50:03 +0800 Muchun Song = wrote: >=20 >> The struct pages could be discontiguous when the kfence pool is = allocated >> via alloc_contig_pages() with CONFIG_SPARSEMEM and = !CONFIG_SPARSEMEM_VMEMMAP. >> So, the iteration should use nth_page(). >=20 > What are the user-visible runtime effects of this flaw? Set the PG_slab and memcg_data to a arbitrary address (may be not used = as a struct page), so the worst case may corrupt the kernel. Thanks. >=20 > Thanks.