From owner-freebsd-bugs@freebsd.org Mon May 22 20:21:57 2017 Return-Path: Delivered-To: freebsd-bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 85540D79AA8 for ; Mon, 22 May 2017 20:21:57 +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 mx1.freebsd.org (Postfix) with ESMTPS id 6BAFB116F for ; Mon, 22 May 2017 20:21:57 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from bugs.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id v4MKLvZS080523 for ; Mon, 22 May 2017 20:21:57 GMT (envelope-from bugzilla-noreply@freebsd.org) From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 219464] [PATCH] linux_getrandom always returns 0 Date: Mon, 22 May 2017 20:21:57 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: CURRENT X-Bugzilla-Keywords: patch X-Bugzilla-Severity: Affects Some People X-Bugzilla-Who: maciej@pasternacki.net X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: freebsd-bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status keywords bug_severity priority component assigned_to reporter 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-bugs@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 22 May 2017 20:21:57 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D219464 Bug ID: 219464 Summary: [PATCH] linux_getrandom always returns 0 Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Keywords: patch Severity: Affects Some People Priority: --- Component: kern Assignee: freebsd-bugs@FreeBSD.org Reporter: maciej@pasternacki.net Created attachment 182818 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=3D182818&action= =3Dedit linux_getrandom.patch In a Linux-based jail, running Ubuntu 16.04, `lsb_release` command (which is widely used in various scripts and during Factorio startup) hangs. `top` sh= ows it forks a `python3.5` process which uses 100% CPU. `truss` shows this proc= ess repeatedly calls `linux_getrandom(=E2=80=A6)`, which always returns 0. `man 2 getrandom` on Ubuntu 16.04 specifies that this syscall should return number of random bytes written (http://man7.org/linux/man-pages/man2/getrandom.2.html). A short test progr= am shows that this it returns positive value on Linux, and returns 0 on FreeBSD despite the fact that random bytes have been written to the buffer: > $ cat test_getrandom.c > #define _GNU_SOURCE > #include > #include > #include > #include >=20 > int main(void) { > int rv; > int buf =3D 0; > rv =3D syscall(SYS_getrandom, &buf, sizeof(buf), GRND_NONBLOCK); > printf("getrandom(&buf, %d, 0) =3D> %d buf=3D%d\n", (int)sizeof(b= uf), rv, buf); > return 0; > } When this program runs natively on Linux, `getrandom(2)` returns size of buffer: > $ ./test_getrandom > getrandom(&buf, 4, 0) =3D> 4 buf=3D-707083248 On FreeBSD 12-CURRENT (possibly also on 11-STABLE, r315505 which introduces this implementation is marked for MFC after 1 month), the syscall always returns 0: > $ ./test_getrandom > getrandom(&buf, 4, 0) =3D> 0 buf=3D-1643413282 After applying attached patch, return value reported from the test program = is the same as on native Linux, and `lsb_release` no longer hangs: > $ ./test_getrandom > getrandom(&buf, 4, 0) =3D> 4 buf=3D-943351330 > $ lsb_release -a > No LSB modules are available. > Distributor ID: Ubuntu > Description: Ubuntu 16.04.2 LTS > Release: 16.04 > Codename: xenial --=20 You are receiving this mail because: You are the assignee for the bug.=