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Howlett" , Vlastimil Babka , Jann Horn , Shuah Khan , Christian Brauner , SeongJae Park , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v2] mm/madvise: reject invalid process_madvise() advice for zero-length vectors Message-ID: References: <637208e9-9d1c-4e7c-8428-9c3d36e2b7da@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <637208e9-9d1c-4e7c-8428-9c3d36e2b7da@kernel.org> X-Stat-Signature: 3ph1mabixztu3gfh9y5bu91ya6ggp6s8 X-Rspamd-Queue-Id: 3C23712000B X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1777359944-870995 X-HE-Meta: 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 ucpV/Yrs /oxriD26gHqW+iauKY5GgzJWrAKsf+wOtnUuw3iGokBuQd+1N15zUnH81WlVI9Z6pu6b+KVSigHs3kYms0TIkgLES17DMR2P+oPbLuham4Nljhd36CdgDLfFsloLV/6PtV7y35MC28g/rT4m1wVjadJodA3OVYMmR/vklstzvdq3vuhb/3URQdcM6DMK13dsKZZURhyrR2w4CsXc6cxFAVmMwXKFwWr9L4XnBpTAdRiD5XA+hnrs6BMQVC46IRif0HyQY9AtONi/ElKYlozS8YJhQfQBz6IPJYPzgOzCfY7r8rOytvFBnVlOloh5WJJp7mHsv Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Apr 27, 2026 at 01:49:46PM +0200, David Hildenbrand (Arm) wrote: > On 4/27/26 11:43, fujunjie wrote: > > process_madvise() used to validate the advice while walking each > > imported iovec. If the vector has zero total length, vector_madvise() > > does not enter the loop and can return success without checking whether > > the advice value is valid. > > > > For a local mm, such as process_madvise(PIDFD_SELF, ...), the remote-only > > process_madvise_remote_valid() check is skipped. As a result, an invalid > > advice can be reported as success when the vector has zero total length. > > This differs from madvise(), which rejects an invalid advice before > > returning success for a zero-length range. > > > > Validate the generic madvise behavior at the syscall-facing entry points > > before any vector walk. In process_madvise(), do this before the > > remote-only advice restriction so unsupported advice is rejected with the > > same priority for local and remote mm. Then keep the per-range helper > > focused on address/length validation, avoiding repeated behavior checks > > for every iovec. > > > > Valid zero-length requests remain no-ops and continue to return 0. Add a > > selftest that covers invalid advice with a zero-length iovec and an empty > > vector, while also checking that a valid zero-length request still > > succeeds. > > > > Fixes: 021781b01275 ("mm/madvise: unrestrict process_madvise() for current process") > > Signed-off-by: fujunjie > > --- > > > Next time, please don't send new revisions as reply to previous submissions. Also this :P email sucks for all this but it makes it easy for me to miss your reply :( Thanks, Lorenzo