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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 4913EC04EB8 for ; Thu, 6 Dec 2018 21:20:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 03C1D2081C for ; Thu, 6 Dec 2018 21:20:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 03C1D2081C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725965AbeLFVUc (ORCPT ); Thu, 6 Dec 2018 16:20:32 -0500 Received: from mx1.redhat.com ([209.132.183.28]:34052 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725928AbeLFVUb (ORCPT ); Thu, 6 Dec 2018 16:20:31 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5B62A9F754; Thu, 6 Dec 2018 21:20:31 +0000 (UTC) Received: from sky.random (ovpn-122-73.rdu2.redhat.com [10.10.122.73]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E360FD1E7; Thu, 6 Dec 2018 21:20:28 +0000 (UTC) From: Andrea Arcangeli To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hugh Dickins , Mike Rapoport , Mike Kravetz , Jann Horn , Peter Xu , "Dr. David Alan Gilbert" Subject: [PATCH 1/1] userfaultfd: check VM_MAYWRITE was set after verifying the uffd is registered Date: Thu, 6 Dec 2018 16:20:28 -0500 Message-Id: <20181206212028.18726-2-aarcange@redhat.com> In-Reply-To: <20181206212028.18726-1-aarcange@redhat.com> References: <20181206212028.18726-1-aarcange@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Thu, 06 Dec 2018 21:20:31 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Calling UFFDIO_UNREGISTER on virtual ranges not yet registered in uffd could trigger an harmless false positive WARN_ON. Check the vma is already registered before checking VM_MAYWRITE to shut off the false positive warning. Cc: Fixes: 29ec90660d68 ("userfaultfd: shmem/hugetlbfs: only allow to register VM_MAYWRITE vmas") Reported-by: syzbot+06c7092e7d71218a2c16@syzkaller.appspotmail.com Signed-off-by: Andrea Arcangeli --- fs/userfaultfd.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index cd58939dc977..7a85e609fc27 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1566,7 +1566,6 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, cond_resched(); BUG_ON(!vma_can_userfault(vma)); - WARN_ON(!(vma->vm_flags & VM_MAYWRITE)); /* * Nothing to do: this vma is already registered into this @@ -1575,6 +1574,8 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, if (!vma->vm_userfaultfd_ctx.ctx) goto skip; + WARN_ON(!(vma->vm_flags & VM_MAYWRITE)); + if (vma->vm_start > start) start = vma->vm_start; vma_end = min(end, vma->vm_end);