From owner-dev-commits-src-all@freebsd.org Fri Sep 17 19:12:36 2021 Return-Path: Delivered-To: dev-commits-src-all@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 457DD6681C2; Fri, 17 Sep 2021 19:12:36 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4HB3Vr0c4dz3Q3Y; Fri, 17 Sep 2021 19:12:36 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id D0C981B269; Fri, 17 Sep 2021 19:12:35 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.16.1/8.16.1) with ESMTP id 18HJCZDe068298; Fri, 17 Sep 2021 19:12:35 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 18HJCZBq068297; Fri, 17 Sep 2021 19:12:35 GMT (envelope-from git) Date: Fri, 17 Sep 2021 19:12:35 GMT Message-Id: <202109171912.18HJCZBq068297@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Mark Johnston Subject: git: 883761f0a81a - main - socket: Remove NOFREE from the socket zone MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: markj X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: 883761f0a81af392893b235632159b15b898e4c6 Auto-Submitted: auto-generated X-BeenThere: dev-commits-src-all@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Commit messages for all branches of the src repository List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 17 Sep 2021 19:12:36 -0000 The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=883761f0a81af392893b235632159b15b898e4c6 commit 883761f0a81af392893b235632159b15b898e4c6 Author: Mark Johnston AuthorDate: 2021-09-17 16:27:26 +0000 Commit: Mark Johnston CommitDate: 2021-09-17 18:19:06 +0000 socket: Remove NOFREE from the socket zone This flag was added during the transition away from the legacy zone allocator, commit c897b81311792ccf6a93feff2a405e2ae53f664e. The old zone allocator effectively provided _NOFREE semantics, but it seems that they are not required for sockets. In particular, we use reference counting to keep sockets live. One somewhat dangerous case is sonewconn(), which returns a pointer to a socket with reference count 0. This socket is still effectively owned by the listening socket. Protocols must therefore be careful to synchronize sonewconn() calls with their pru_close implementations, since for listening sockets soclose() will abort the child sockets. For example, TCP holds the listening socket's PCB read locked across the sonewconn() call, which blocks tcp_usr_close(), and sofree() synchronizes with a concurrent soabort() of the nascent socket. However, _NOFREE semantics are not required here. Eliminating _NOFREE has several benefits: it enables use-after-free detection (e.g., by KASAN) and lets the system reclaim memory from the socket zone under memory pressure. No functional change intended. Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D31975 --- sys/kern/uipc_socket.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sys/kern/uipc_socket.c b/sys/kern/uipc_socket.c index 9e898861f8f4..c3f52a4640d3 100644 --- a/sys/kern/uipc_socket.c +++ b/sys/kern/uipc_socket.c @@ -309,7 +309,7 @@ socket_init(void *tag) { socket_zone = uma_zcreate("socket", sizeof(struct socket), NULL, NULL, - NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); + NULL, NULL, UMA_ALIGN_PTR, 0); maxsockets = uma_zone_set_max(socket_zone, maxsockets); uma_zone_set_warning(socket_zone, "kern.ipc.maxsockets limit reached"); EVENTHANDLER_REGISTER(maxsockets_change, socket_zone_change, NULL,