From patchwork Tue Apr 26 08:20:50 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 566523 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA018C433F5 for ; Tue, 26 Apr 2022 09:04:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241769AbiDZJHY (ORCPT ); Tue, 26 Apr 2022 05:07:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38470 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347537AbiDZJFz (ORCPT ); Tue, 26 Apr 2022 05:05:55 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F144F12FECE; Tue, 26 Apr 2022 01:44:54 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A1E36B81CFE; Tue, 26 Apr 2022 08:44:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E4494C385A0; Tue, 26 Apr 2022 08:44:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1650962692; bh=5xTDvNXwoCQJk1iKzJHupHTTjUGUOgb2bv+ABVlDzXk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H4klwte6T2nI2vC5kuR+mRGDbi/Mgc1MoinXI8qmLCc/QCu8iJPtvrUUqvrURBBIa h66/442zMLJhlG+4BvST9K1zx69T9ROsZtpkohZ12SSujha7357hqE7ERJVYYFS2S6 ADXTCOILiJ0feq//QeRDDp3bNG3rdHRlzAna5f64= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nadav Amit , Peter Xu , Axel Rasmussen , Mike Rapoport , Andrea Arcangeli , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 5.17 055/146] userfaultfd: mark uffd_wp regardless of VM_WRITE flag Date: Tue, 26 Apr 2022 10:20:50 +0200 Message-Id: <20220426081751.615934458@linuxfoundation.org> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220426081750.051179617@linuxfoundation.org> References: <20220426081750.051179617@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Nadav Amit [ Upstream commit 0e88904cb700a9654c9f0d9ca4967e761e7c9ee8 ] When a PTE is set by UFFD operations such as UFFDIO_COPY, the PTE is currently only marked as write-protected if the VMA has VM_WRITE flag set. This seems incorrect or at least would be unexpected by the users. Consider the following sequence of operations that are being performed on a certain page: mprotect(PROT_READ) UFFDIO_COPY(UFFDIO_COPY_MODE_WP) mprotect(PROT_READ|PROT_WRITE) At this point the user would expect to still get UFFD notification when the page is accessed for write, but the user would not get one, since the PTE was not marked as UFFD_WP during UFFDIO_COPY. Fix it by always marking PTEs as UFFD_WP regardless on the write-permission in the VMA flags. Link: https://lkml.kernel.org/r/20220217211602.2769-1-namit@vmware.com Fixes: 292924b26024 ("userfaultfd: wp: apply _PAGE_UFFD_WP bit") Signed-off-by: Nadav Amit Acked-by: Peter Xu Cc: Axel Rasmussen Cc: Mike Rapoport Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- mm/userfaultfd.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 0780c2a57ff1..885e5adb0168 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -72,12 +72,15 @@ int mfill_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, _dst_pte = pte_mkdirty(_dst_pte); if (page_in_cache && !vm_shared) writable = false; - if (writable) { - if (wp_copy) - _dst_pte = pte_mkuffd_wp(_dst_pte); - else - _dst_pte = pte_mkwrite(_dst_pte); - } + + /* + * Always mark a PTE as write-protected when needed, regardless of + * VM_WRITE, which the user might change. + */ + if (wp_copy) + _dst_pte = pte_mkuffd_wp(_dst_pte); + else if (writable) + _dst_pte = pte_mkwrite(_dst_pte); dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);