From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 59F91C31E45 for ; Thu, 13 Jun 2019 15:44:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2885921773 for ; Thu, 13 Jun 2019 15:44:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728142AbfFMPoT (ORCPT ); Thu, 13 Jun 2019 11:44:19 -0400 Received: from mx2.suse.de ([195.135.220.15]:52646 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728340AbfFMPoQ (ORCPT ); Thu, 13 Jun 2019 11:44:16 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 7C183AD2B; Thu, 13 Jun 2019 15:44:15 +0000 (UTC) Date: Thu, 13 Jun 2019 17:44:15 +0200 Message-ID: From: Takashi Iwai To: Sasha Levin Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, stable@vger.kernel.org, syzbot+e4c8abb920efa77bace9@syzkaller.appspotmail.com Subject: Re: [PATCH 4.14 61/81] ALSA: seq: Protect in-kernel ioctl calls with mutex In-Reply-To: <20190613153946.GG1513@sasha-vm> References: <20190613075649.074682929@linuxfoundation.org> <20190613075653.581995283@linuxfoundation.org> <20190613091122.GA31122@kroah.com> <20190613153946.GG1513@sasha-vm> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 13 Jun 2019 17:39:46 +0200, Sasha Levin wrote: > > On Thu, Jun 13, 2019 at 11:13:55AM +0200, Takashi Iwai wrote: > >On Thu, 13 Jun 2019 11:11:22 +0200, > >Greg Kroah-Hartman wrote: > >> > >> On Thu, Jun 13, 2019 at 11:02:54AM +0200, Takashi Iwai wrote: > >> > On Thu, 13 Jun 2019 10:33:44 +0200, > >> > Greg Kroah-Hartman wrote: > >> > > > >> > > [ Upstream commit feb689025fbb6f0aa6297d3ddf97de945ea4ad32 ] > >> > > > >> > > ALSA OSS sequencer calls the ioctl function indirectly via > >> > > snd_seq_kernel_client_ctl(). While we already applied the protection > >> > > against races between the normal ioctls and writes via the client's > >> > > ioctl_mutex, this code path was left untouched. And this seems to be > >> > > the cause of still remaining some rare UAF as spontaneously triggered > >> > > by syzkaller. > >> > > > >> > > For the sake of robustness, wrap the ioctl_mutex also for the call via > >> > > snd_seq_kernel_client_ctl(), too. > >> > > > >> > > Reported-by: syzbot+e4c8abb920efa77bace9@syzkaller.appspotmail.com > >> > > Signed-off-by: Takashi Iwai > >> > > Signed-off-by: Sasha Levin > >> > > >> > This commit is reverted later by commit f0654ba94e33. > >> > So please drop this. The proper fix is done later by commit > >> > 7c32ae35fbf9 ("ALSA: seq: Cover unsubscribe_port() in list_mutex") > >> > > >> > Ditto for 4.19.y and 5.1.y. > >> > >> Now dropped everywhere, and I added 7c32ae35fbf9 ("ALSA: seq: Cover > >> unsubscribe_port() in list_mutex") everywhere instead. > > > >Thanks! > > > >BTW, do we have a systematic check whether the selected stable commit > >is reverted in a later commit? At least, you can track it as long as > >Fixes tag is properly set. > > I have that scripting in place, and I usually check it once before I > send the initial reviews and then once Greg does the -rc release. OK, good to hear. So this time must be some exceptional error. thanks, Takashi