From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757984AbcASWvo (ORCPT ); Tue, 19 Jan 2016 17:51:44 -0500 Received: from out02.mta.xmission.com ([166.70.13.232]:34469 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757914AbcASWvh (ORCPT ); Tue, 19 Jan 2016 17:51:37 -0500 From: ebiederm@xmission.com (Eric W. Biederman) To: Al Viro Cc: Dan Carpenter , kernel-hardening@lists.openwall.com, linux-kernel@vger.kernel.org References: <20160119112812.GA10818@mwanda> <20160119180009.GT17997@ZenIV.linux.org.uk> Date: Tue, 19 Jan 2016 16:41:55 -0600 In-Reply-To: <20160119180009.GT17997@ZenIV.linux.org.uk> (Al Viro's message of "Tue, 19 Jan 2016 18:00:09 +0000") Message-ID: <87h9i95gzw.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: U2FsdGVkX1+bHQ9HE+so7wsIdxg/1q6PSYjKWEX72lk= 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: 0.4999] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa06 1397; Body=1 Fuz1=1 Fuz2=1] X-Spam-DCC: XMission; sa06 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Al Viro X-Spam-Relay-Country: X-Spam-Timing: total 5840 ms - load_scoreonly_sql: 0.03 (0.0%), signal_user_changed: 3.2 (0.1%), b_tie_ro: 2.3 (0.0%), parse: 0.90 (0.0%), extract_message_metadata: 18 (0.3%), get_uri_detail_list: 1.66 (0.0%), tests_pri_-1000: 7 (0.1%), tests_pri_-950: 1.59 (0.0%), tests_pri_-900: 1.42 (0.0%), tests_pri_-400: 23 (0.4%), check_bayes: 22 (0.4%), b_tokenize: 7 (0.1%), b_tok_get_all: 6 (0.1%), b_comp_prob: 2.7 (0.0%), b_tok_touch_all: 3.3 (0.1%), b_finish: 0.64 (0.0%), tests_pri_0: 254 (4.4%), check_dkim_signature: 0.65 (0.0%), check_dkim_adsp: 111 (1.9%), tests_pri_500: 5527 (94.6%), poll_dns_idle: 5522 (94.6%), rewrite_mail: 0.00 (0.0%) Subject: Re: [kernel-hardening] Re: 2015 kernel CVEs 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 in02.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Al Viro writes: > On Tue, Jan 19, 2016 at 02:28:12PM +0300, Dan Carpenter wrote: >> CVE-2015-4178 820f9f147dcc: fs_pin: uninitialized data > > Why is that a CVE? Affected code is in pin_remove(), which is only > called from fs_pin ->kill() instances; if one is _ever_ called more > than once per fs_pin lifetime, we are already FUBAR. If Eric had > ever intended to add checks for hlist_unhashed() on those lists, > such checks never had been added to the tree. They definitely did not > exist at the moment when that commit went in. > > It got merged mostly on the "it doesn't harm anything and it's a bit > more tidy that way" basis; if it had ever changed behaviour in any visible > way, *THEN* we had a real problem and that problem was not fixed by that > commit, so I would really like to see the details - simply to make sure > that the damn thing had been eventually fixed. > > Eric, could you explain? And could whoever'd been responsible for > that CVE describe the process that had lead to its creation? As best I know this was an issue because someone borked a backport, and skipped this patch. As I recall hlist_del_init was needed because in one instance one of the lists was not used. Which is actually what it says in the description of 820f9f147dcc so I will leave it at that. Eric