Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754302AbbLTJwi (ORCPT ); Sun, 20 Dec 2015 04:52:38 -0500 Received: from out02.mta.xmission.com ([166.70.13.232]:46030 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754251AbbLTJwf (ORCPT ); Sun, 20 Dec 2015 04:52:35 -0500 From: ebiederm@xmission.com (Eric W. Biederman) To: "H. Peter Anvin" Cc: Peter Hurley , Greg KH , Jiri Slaby , Linus Torvalds , Aurelien Jarno , Andy Lutomirski , Florian Weimer , Al Viro , Serge Hallyn , Jann Horn , "security\@kernel.org" , "security\@ubuntu.com \>\> security" , security@debian.org, Willy Tarreau , linux-kernel@vger.kernel.org References: <43AD2BA7-B594-4299-95F3-D86FD38AF21B@zytor.com> <87egexpf4o.fsf@x220.int.ebiederm.org> <1CB621EF-1647-463B-A144-D611DB150E15@zytor.com> <20151208223135.GA8352@kroah.com> <87oae0h2bo.fsf@x220.int.ebiederm.org> <56677DE3.5040705@zytor.com> <20151209012311.GA11794@kroah.com> <84B136DF-55E4-476A-9CB2-062B15677EE5@zytor.com> <20151209013859.GA12442@kroah.com> <20151209083225.GA30452@1wt.eu> <87wpskyds7.fsf_-_@x220.int.ebiederm.org> <566F1CD7.20502@hurleysoftware.com> <87y4cq6t1j.fsf@x220.int.ebiederm.org> <87a8p54v3t.fsf@x220.int.ebiederm.org> <5AFEA8FF-BDEA-40AF-8C45-19F3E9CC36D3@zytor.com> Date: Sun, 20 Dec 2015 03:42:34 -0600 In-Reply-To: <5AFEA8FF-BDEA-40AF-8C45-19F3E9CC36D3@zytor.com> (H. Peter Anvin's message of "Sat, 19 Dec 2015 20:35:29 -0800") Message-ID: <87r3ih1mnp.fsf@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-AID: U2FsdGVkX184GdfUDQBvfoGXt9BoCs5z+PTv9CGSFiE= X-SA-Exim-Connect-IP: 97.121.81.63 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 TVD_RCVD_IP Message was received from an IP address * 0.0 T_TM2_M_HEADER_IN_MSG BODY: No description available. * 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60% * [score: 0.5000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa03 1397; Body=1 Fuz1=1 Fuz2=1] X-Spam-DCC: XMission; sa03 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;"H. Peter Anvin" X-Spam-Relay-Country: X-Spam-Timing: total 1143 ms - load_scoreonly_sql: 0.05 (0.0%), signal_user_changed: 3.7 (0.3%), b_tie_ro: 2.6 (0.2%), parse: 1.26 (0.1%), extract_message_metadata: 24 (2.1%), get_uri_detail_list: 1.43 (0.1%), tests_pri_-1000: 10 (0.9%), tests_pri_-950: 2.1 (0.2%), tests_pri_-900: 1.67 (0.1%), tests_pri_-400: 30 (2.6%), check_bayes: 28 (2.5%), b_tokenize: 11 (1.0%), b_tok_get_all: 7 (0.6%), b_comp_prob: 3.5 (0.3%), b_tok_touch_all: 2.6 (0.2%), b_finish: 0.82 (0.1%), tests_pri_0: 927 (81.1%), check_dkim_signature: 0.84 (0.1%), check_dkim_adsp: 4.5 (0.4%), tests_pri_500: 138 (12.0%), poll_dns_idle: 128 (11.2%), rewrite_mail: 0.00 (0.0%) Subject: Re: [PATCH] devpts: Sensible /dev/ptmx & force newinstance X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Wed, 24 Sep 2014 11:00:52 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1137 Lines: 30 "H. Peter Anvin" writes: > Does it matter if it mounts devpts twice? It seems like a waste of a > minuscule amount of memory, and nothing else. It breaks system("mknod /tmp/ptmx c 5 2"); open("/tmp/ptmx"); As it opens a pty in an inaccessible instance of devpts. When previously the instance of devpts was accessible. So backwards compatibility is broken. It doubly matters as we have evidence that b0rken userspace actually does that things like that. I will probably get a grumble or two but it turns out it isn't particularly hard to deal with the overmounting that happens in CentOS6, and the mounting then unmounting then mounting again that happens in CentOS5, and openwrt. For the cases I know to test for I have something that works now. I am going to sleep on it and then see if I can find think of other things to test before I push out a patch. Eric -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/