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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 C335AC3A589 for ; Tue, 20 Aug 2019 16:05:35 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 90C3722DA9 for ; Tue, 20 Aug 2019 16:05:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 90C3722DA9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 607026B000E; Tue, 20 Aug 2019 12:05:34 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5B7C36B0010; Tue, 20 Aug 2019 12:05:34 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4CD4D6B0266; Tue, 20 Aug 2019 12:05:34 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0112.hostedemail.com [216.40.44.112]) by kanga.kvack.org (Postfix) with ESMTP id 2525D6B000E for ; Tue, 20 Aug 2019 12:05:34 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id C673C8248AB6 for ; Tue, 20 Aug 2019 16:05:33 +0000 (UTC) X-FDA: 75843281346.02.coal18_1366ffc30a34a X-HE-Tag: coal18_1366ffc30a34a X-Filterd-Recvd-Size: 2471 Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by imf11.hostedemail.com (Postfix) with ESMTP for ; Tue, 20 Aug 2019 16:05:33 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 197CB300BE7F; Tue, 20 Aug 2019 16:05:32 +0000 (UTC) Received: from mail (ovpn-120-35.rdu2.redhat.com [10.10.120.35]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 406035D9D5; Tue, 20 Aug 2019 16:05:27 +0000 (UTC) Date: Tue, 20 Aug 2019 12:05:25 -0400 From: Andrea Arcangeli To: Oleg Nesterov Cc: Kefeng Wang , linux-mm , Peter Xu , Mike Rapoport , Jann Horn , Jason Gunthorpe , Michal Hocko , Andrew Morton , Tetsuo Handa , linux-kernel@vger.kernel.org Subject: Re: [PATCH] userfaultfd_release: always remove uffd flags and clear vm_userfaultfd_ctx Message-ID: <20190820160525.GN31518@redhat.com> References: <20190820160237.GB4983@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190820160237.GB4983@redhat.com> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Tue, 20 Aug 2019 16:05:32 +0000 (UTC) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Aug 20, 2019 at 06:02:38PM +0200, Oleg Nesterov wrote: > userfaultfd_release() should clear vm_flags/vm_userfaultfd_ctx even > if mm->core_state != NULL. > > Otherwise a page fault can see userfaultfd_missing() == T and use an > already freed userfaultfd_ctx. > > Reported-by: Kefeng Wang > Fixes: 04f5866e41fb ("coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping") > Cc: stable@vger.kernel.org > Signed-off-by: Oleg Nesterov > --- > fs/userfaultfd.c | 25 +++++++++++++------------ > 1 file changed, 13 insertions(+), 12 deletions(-) Reviewed-by: Andrea Arcangeli Thanks, Andrea