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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Willem de Bruijn , David Ahern , Matthew Wilcox , Christoph Hellwig , Jens Axboe , Jeff Layton , Christian Brauner , Chuck Lever III , Linus Torvalds , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Willem de Bruijn Subject: Re: [PATCH net-next v6 01/18] net: Declare MSG_SPLICE_PAGES internal sendmsg() flag Message-ID: <20230413042917.GA3390869@ZenIV> References: <20230411160902.4134381-1-dhowells@redhat.com> <20230411160902.4134381-2-dhowells@redhat.com> <20230413005129.GZ3390869@ZenIV> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230413005129.GZ3390869@ZenIV> X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: ez5weoeubyefcpijyknu5bhm3hheeqnn X-Rspamd-Queue-Id: 0AE53C0004 X-HE-Tag: 1681360177-268976 X-HE-Meta: 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 a8KYBIJq Fq3bYC2yXbQWVEosU80CVmBn3+Ng7HZ8izkq96+HBggPyyO6G217iclokVslQq12v1V1kM6eD+8+b3EaonueeJnFFGcGMl23BeYoN7SFzJbCLKBa5OgkVhGdMQYNC/P/8XoBBl8PwV4/Y2fHOAHYxpNCORFUicfEz8WF1btm1mua1AjwBGd5jOSWRCPR5sBm/WjO6jMFH4p9XwBnApqC95ydDED/9LCcYHPMrpSBJARfupRTXiDu2Nx1rTYcs8KPK4eZq0UdfDrOFzlIVM2QRbtPSGcVsSioXFFPWnQOIZLN3Bl8Q1hu7TgEb6HBL7djlJ+di/1/nEv44m0bkRMgctvgmqMcw+MXEEM5koQI8aoI/cmozBTKB9B5skhokxwajzKXWiGrSCJSSYgYel+Qdf9kbOeR/TgJmRFkZKlIPlycoIKvncEtNX0DA5SwDcE0eIPrHs1raf7m+xH3fMnuNr1Kb8OKlbm/CU+5bDOtnej0Yj5c= 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 Thu, Apr 13, 2023 at 01:51:29AM +0100, Al Viro wrote: > On Tue, Apr 11, 2023 at 05:08:45PM +0100, David Howells wrote: > > > @@ -2483,6 +2484,7 @@ static int ____sys_sendmsg(struct socket *sock, struct msghdr *msg_sys, > > } > > msg_sys->msg_flags = flags; > > > > + flags &= ~MSG_INTERNAL_SENDMSG_FLAGS; > > if (sock->file->f_flags & O_NONBLOCK) > > msg_sys->msg_flags |= MSG_DONTWAIT; > > A bit too late, innit? There's no users of 'flags' downstream of that > assignment to ->msg_flags, so your &= is a no-op; it should be done > *before* that assignment... While we are at it, io-uring has this: int io_sendmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) { struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg); ... sr->msg_flags = READ_ONCE(sqe->msg_flags) | MSG_NOSIGNAL; and int io_send(struct io_kiocb *req, unsigned int issue_flags) { struct sockaddr_storage __address; struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg); ... flags = sr->msg_flags; if (issue_flags & IO_URING_F_NONBLOCK) flags |= MSG_DONTWAIT; if (flags & MSG_WAITALL) min_ret = iov_iter_count(&msg.msg_iter); msg.msg_flags = flags; ret = sock_sendmsg(sock, &msg); Note that io_sendmsg_prep() handles both IORING_OP_SENDMSG and IORING_OP_SEND, so this pair of functions can hit the same request. And sqe->msg_flags is not sanitized at all - it comes straight from user buffer.