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Mon, 07 Oct 2024 08:01:19 -0700 (PDT) MIME-Version: 1.0 References: <20241001002628.2239032-1-jeffxu@chromium.org> <20241001002628.2239032-2-jeffxu@chromium.org> <4544a4b3-d5b6-4f6b-b3d5-6c309eb8fa9d@infradead.org> <78f05735-cca3-491e-b2d6-c673427efa07@infradead.org> In-Reply-To: <78f05735-cca3-491e-b2d6-c673427efa07@infradead.org> From: Jeff Xu Date: Mon, 7 Oct 2024 08:01:00 -0700 Message-ID: Subject: Re: [PATCH v2 1/1] mseal: update mseal.rst To: Randy Dunlap Cc: akpm@linux-foundation.org, keescook@chromium.org, corbet@lwn.net, jorgelo@chromium.org, groeck@chromium.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, jannh@google.com, sroettger@google.com, pedro.falcato@gmail.com, linux-hardening@vger.kernel.org, willy@infradead.org, gregkh@linuxfoundation.org, torvalds@linux-foundation.org, deraadt@openbsd.org, usama.anjum@collabora.com, surenb@google.com, merimus@google.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, enh@google.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: 7qp7khxu6p7w8nhnw1kykdx4gzoi69wh X-Rspamd-Queue-Id: 869C71A001F X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1728313280-750064 X-HE-Meta: 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 5BmG92pb f2OB+Djb+JsxZdQRY9RccDqSlgNrJL+7XOLywQ4PDxcS07v+dt/+DayxMS05JmxGF56VaseFa9TgC7n6djObZXyj9CCDzy+5Zt6TfTSzAaT7qjwI1RwnGT6DdFAFBwkD5I08QsocjKnVOKGKAC/Q3I93LHiTXtxF+ohOFhSu0iOx8wPul533vjVWhwbTfvaXiuFSVp/IWBWh9hA0h5TYBWX9d2s6eazPjEXxOGbtAF4Cp0TT3SbPkra5n6yCDZVGirr8roWTqpAvhbDHwzmPwtv0s9tHBCcY3ubMkTEBiSiNkatHkiHQtKH3Qjbt/hfhihad0nPa9HHsEghU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000003, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Randy On Fri, Oct 4, 2024 at 4:52=E2=80=AFPM Randy Dunlap = wrote: > > > > On 10/4/24 9:52 AM, Jeff Xu wrote: > >> above is not a sentence but I don't know how to fix it. > >> > > Would below work ? > > > > Certain destructive madvise behaviors, specifically MADV_DONTNEED, > > MADV_FREE, MADV_DONTNEED_LOCKED, MADV_FREE, MADV_DONTFORK, > > MADV_WIPEONFORK, can pose risks when applied to anonymous memory by > > threads without write permissions. These behaviors have the potential > > to modify region contents by discarding pages, effectively performing > > a memset(0) operation on the anonymous memory. > > Yes, that works. > Or at least it explains the problem, like Theo said. > I updated with : Certain destructive madvise behaviors, specifically MADV_DONTNEED, MADV_FREE, MADV_DONTNEED_LOCKED, and MADV_WIPEONFORK, can introduce risks when applied to anonymous memory by threads lacking write permissions. Consequently, these operations are prohibited under such conditions. The aforementioned behaviors have the potential to modify region contents by discarding pages, effectively performing a memset(0) operation on the anonymous memory. Thanks -Jeff > Thanks. > -- > ~Randy