From owner-freebsd-net@freebsd.org Thu Dec 27 11:25:50 2018 Return-Path: Delivered-To: freebsd-net@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 75B89135A355 for ; Thu, 27 Dec 2018 11:25:50 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mailman.ysv.freebsd.org (mailman.ysv.freebsd.org [IPv6:2001:1900:2254:206a::50:5]) by mx1.freebsd.org (Postfix) with ESMTP id 02DF76EF04 for ; Thu, 27 Dec 2018 11:25:50 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.ysv.freebsd.org (Postfix) id B51C9135A354; Thu, 27 Dec 2018 11:25:49 +0000 (UTC) Delivered-To: net@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 77BDB135A353 for ; Thu, 27 Dec 2018 11:25:49 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.ysv.freebsd.org (mxrelay.ysv.freebsd.org [IPv6:2001:1900:2254:206a::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.ysv.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 13DBB6EEFC for ; Thu, 27 Dec 2018 11:25:49 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2001:1900:2254:206a::16:76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.ysv.freebsd.org (Postfix) with ESMTPS id 4F9E82AE6 for ; Thu, 27 Dec 2018 11:25:48 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id wBRBPm6L008028 for ; Thu, 27 Dec 2018 11:25:48 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id wBRBPmnq008027 for net@FreeBSD.org; Thu, 27 Dec 2018 11:25:48 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: www set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: net@FreeBSD.org Subject: [Bug 234442] libnetgraph race condition Date: Thu, 27 Dec 2018 11:25:47 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: bin X-Bugzilla-Version: 11.2-STABLE X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Some People X-Bugzilla-Who: eugen@freebsd.org X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: net@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter cc attachments.created Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 27 Dec 2018 11:25:50 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D234442 Bug ID: 234442 Summary: libnetgraph race condition Product: Base System Version: 11.2-STABLE Hardware: Any OS: Any Status: New Severity: Affects Some People Priority: --- Component: bin Assignee: net@FreeBSD.org Reporter: eugen@freebsd.org CC: avg@FreeBSD.org, glebius@FreeBSD.org, kib@FreeBSD.org, mav@FreeBSD.org Created attachment 200557 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=3D200557&action= =3Dedit fight race with mutex Hi! lib/libnetgraph/msg.c defines static int gMsgId and public functions NgSendMsg() and NgSendAsciiMsg() that both increment gMsgId in racy way in attempt to produce unique id for a request sent over AF_NETGRAPH socket. For long-lived multi-threaded application like net/mpd5 daemon: first thread can increase gMsgId upto INT_MAX and next moment another thread can increate gMsgId again to become -1. Then it is copied to unsigned msg.header.token a= nd returned as signed integer. This means false error status returned with errno=3D=3D0 and this breaks workflow of the daemon. I get this problem "in= wild" from time to time. I have very straightforward and naive patch protecting the variable with si= mple mutex (attached) but it has its penalty for performance. Usage of atomic operations should be better approach but I'm not familiar w= ith FreeBSD atomic operations. Any help will be appreciated. --=20 You are receiving this mail because: You are the assignee for the bug.=