From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=MAILING_LIST_MULTI, RCVD_IN_MSPIKE_H2 autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 16235 invoked from network); 27 Feb 2023 22:38:40 -0000 Received: from second.openwall.net (193.110.157.125) by inbox.vuxu.org with ESMTPUTF8; 27 Feb 2023 22:38:40 -0000 Received: (qmail 21799 invoked by uid 550); 27 Feb 2023 22:38:37 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: musl@lists.openwall.com Received: (qmail 21764 invoked from network); 27 Feb 2023 22:38:36 -0000 Date: Mon, 27 Feb 2023 17:38:23 -0500 From: Rich Felker To: musl@lists.openwall.com Message-ID: <20230227223822.GH4163@brightrain.aerifal.cx> References: <20230227194654.61114-1-izbyshev@ispras.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230227194654.61114-1-izbyshev@ispras.ru> User-Agent: Mutt/1.5.21 (2010-09-15) Subject: Re: [musl] [PATCH] accept4: don't fall back to accept if we got unknown flags On Mon, Feb 27, 2023 at 10:46:54PM +0300, Alexey Izbyshev wrote: > accept4 emulation via accept ignores unknown flags, so it can spuriously > succeed instead of failing (or succeed without doing the action implied > by an unknown flag if it's added in a future kernel). Worse, unknown > flags trigger the fallback code even on modern kernels if the real > accept4 syscall returns EINVAL, because this is indistinguishable from > socketcall returning EINVAL due to lack of accept4 support. Fix this by > always propagating the syscall attempt failure if unknown flags are > present. > > The behavior is still not ideal on old kernels lacking accept4 on arches > with socketcall, where failing with ENOSYS instead of EINVAL returned by > socketcall would be preferable, but at least modern kernels are now > fine. Can you clarify what you mean about ENOSYS vs EINVAL here? I'm not following. Rich