From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751892AbdLSS16 (ORCPT ); Tue, 19 Dec 2017 13:27:58 -0500 Received: from out03.mta.xmission.com ([166.70.13.233]:45544 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750798AbdLSS1z (ORCPT ); Tue, 19 Dec 2017 13:27:55 -0500 From: ebiederm@xmission.com (Eric W. Biederman) To: Dave Jones Cc: Linus Torvalds , Al Viro , Linux Kernel References: <20171218214438.GA32728@codemonkey.org.uk> <20171218221541.GP21978@ZenIV.linux.org.uk> <20171218231013.GA9481@codemonkey.org.uk> <20171219033926.GA26981@codemonkey.org.uk> Date: Tue, 19 Dec 2017 12:27:30 -0600 In-Reply-To: <20171219033926.GA26981@codemonkey.org.uk> (Dave Jones's message of "Mon, 18 Dec 2017 22:39:26 -0500") Message-ID: <87lghy7eul.fsf@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1eRMcL-0004rC-RG;;;mid=<87lghy7eul.fsf@xmission.com>;;;hst=in01.mta.xmission.com;;;ip=75.170.127.89;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1/KZ1K11fyM1vcclWds4NzhgENhJ9vrsZc= X-SA-Exim-Connect-IP: 75.170.127.89 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 * [sa06 1397; Body=1 Fuz1=1 Fuz2=1] * 1.0 T_XMDrugObfuBody_08 obfuscated drug references X-Spam-DCC: XMission; sa06 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Dave Jones X-Spam-Relay-Country: X-Spam-Timing: total 184 ms - load_scoreonly_sql: 0.04 (0.0%), signal_user_changed: 3.1 (1.7%), b_tie_ro: 2.2 (1.2%), parse: 0.75 (0.4%), extract_message_metadata: 10 (5.3%), get_uri_detail_list: 0.92 (0.5%), tests_pri_-1000: 4.6 (2.5%), tests_pri_-950: 1.24 (0.7%), tests_pri_-900: 0.99 (0.5%), tests_pri_-400: 18 (10.0%), check_bayes: 17 (9.4%), b_tokenize: 5 (2.8%), b_tok_get_all: 6 (3.2%), b_comp_prob: 1.94 (1.1%), b_tok_touch_all: 2.4 (1.3%), b_finish: 0.64 (0.3%), tests_pri_0: 138 (75.3%), check_dkim_signature: 0.45 (0.2%), check_dkim_adsp: 2.5 (1.3%), tests_pri_500: 3.8 (2.1%), rewrite_mail: 0.00 (0.0%) Subject: Re: proc_flush_task oops X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -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 Dave Jones writes: > On Mon, Dec 18, 2017 at 03:50:52PM -0800, Linus Torvalds wrote: > > > But I don't see what would have changed in this area recently. > > > > Do you end up saving the seeds that cause crashes? Is this > > reproducible? (Other than seeing it twoce, of course) > > Only clue so far, is every time I'm able to trigger it, the last thing > the child process that triggers it did, was an execveat. Is there any chance the excveat might be called from a child thread? That switching pids between tasks of a process during exec can get a little bit tricky. > Telling it to just fuzz execveat doesn't instantly trigger it, so it > must be a combination of some other syscall. I'll leave a script running > overnight to see if I can binary search the other syscalls in > combination with it. Could we have a buggy syscall that is stomping something? > One other thing: I said this was rc4, but it was actually rc4 + all the > x86 stuff from today. There's enough creepy stuff in that pile, that > I'll try with just plain rc4 tomorrow too. Eric