From owner-freebsd-bugs@freebsd.org Sun Feb 10 20:58:15 2019 Return-Path: Delivered-To: freebsd-bugs@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 B814A14DB88D for ; Sun, 10 Feb 2019 20:58:14 +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 4A28D6A73E for ; Sun, 10 Feb 2019 20:58:14 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.ysv.freebsd.org (Postfix) id 0ACCC14DB88C; Sun, 10 Feb 2019 20:58:14 +0000 (UTC) Delivered-To: bugs@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 EAEC214DB88B for ; Sun, 10 Feb 2019 20:58:13 +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 822D06A739 for ; Sun, 10 Feb 2019 20:58:13 +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 D5E8E15EF8 for ; Sun, 10 Feb 2019 20:58:12 +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 x1AKwCmI034271 for ; Sun, 10 Feb 2019 20:58:12 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id x1AKwCtO034270 for bugs@FreeBSD.org; Sun, 10 Feb 2019 20:58:12 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: bugs@FreeBSD.org Subject: [Bug 76972] [kernel] [patch] 64-bit integer overflow computing user cpu time in calcru() in kern_resource.c Date: Sun, 10 Feb 2019 20:58:13 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: unspecified X-Bugzilla-Keywords: patch, patch-ready X-Bugzilla-Severity: Affects Only Me X-Bugzilla-Who: cem@freebsd.org X-Bugzilla-Status: In Progress X-Bugzilla-Resolution: X-Bugzilla-Priority: Normal X-Bugzilla-Assigned-To: cem@freebsd.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: assigned_to keywords bug_status cc Message-ID: In-Reply-To: References: 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-bugs@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 10 Feb 2019 20:58:15 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D76972 Conrad Meyer changed: What |Removed |Added ---------------------------------------------------------------------------- Assignee|bugs@FreeBSD.org |cem@freebsd.org Keywords| |patch, patch-ready Status|Open |In Progress CC| |cem@freebsd.org --- Comment #6 from Conrad Meyer --- I wrote a small program to empirically validate the proposed patch under so= me assumptions. "tu" (total time in microseconds) is drawn from [1, ~1000 years] (0 is uninteresting). "tt" (total time in ticks) is tu / 1000. "ut" or "st" is <=3D tt. With randomly drawn tu and ut/st in the given ranges (not precisely uniform= due to lack of arc4random_uniform64, but close to uniform distribution), I obse= rve overflow in something like 99.999976% of the input range with the current algorithm and 0% (absolutely zero) instances of overflow with the proposed patch. Also, the result is correct, and not truncated, in all cases with t= he bounds given above. I believe it fixes the issue and can be committed. --=20 You are receiving this mail because: You are the assignee for the bug.=