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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 67AD7C46467 for ; Thu, 15 Dec 2022 21:52:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229475AbiLOVwG (ORCPT ); Thu, 15 Dec 2022 16:52:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46296 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229868AbiLOVwC (ORCPT ); Thu, 15 Dec 2022 16:52:02 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 78C4E442F0; Thu, 15 Dec 2022 13:52:01 -0800 (PST) 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 35BFCB81CC0; Thu, 15 Dec 2022 21:52:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D7EE6C433D2; Thu, 15 Dec 2022 21:51:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1671141118; bh=iwvxEdyfXUm7cviwQ12hHMS0tUNEL3EVkx8xU4xxOw0=; h=Date:To:From:Subject:From; b=cL6cPXZYWP+fdHHnvN905ChgmIGGKrxzqPcOoiRKDMxZr4UjTzj8fmRc6Finpkmdv zHkmvSbSqP/x839PnoIqwJJtxoqTPvl4MzdmXHbLOtOjqgw9HDl046CQk1ILw6Hpnf WYQW8HQx0bybmoKtqmaud6vtA0Rc52V0f101z8Zw= Date: Thu, 15 Dec 2022 13:51:58 -0800 To: mm-commits@vger.kernel.org, ying.huang@intel.com, stable@vger.kernel.org, pengfei.xu@intel.com, nadav.amit@gmail.com, linmiaohe@huawei.com, david@redhat.com, aarcange@redhat.com, peterx@redhat.com, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-uffd-fix-pte-marker-when-fork-without-fork-event.patch added to mm-hotfixes-unstable branch Message-Id: <20221215215158.D7EE6C433D2@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm/uffd: fix pte marker when fork() without fork event has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-uffd-fix-pte-marker-when-fork-without-fork-event.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-uffd-fix-pte-marker-when-fork-without-fork-event.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Peter Xu Subject: mm/uffd: fix pte marker when fork() without fork event Date: Wed, 14 Dec 2022 15:04:52 -0500 Patch series "mm: Fixes on pte markers". Patch 1 resolves the syzkiller report from Pengfei. Patch 2 further harden pte markers when used with the recent swapin error markers. The major case is we should persist a swapin error marker after fork(), so child shouldn't read a corrupted page. This patch (of 2): When fork(), dst_vma is not guaranteed to have VM_UFFD_WP even if src may have it and has pte marker installed. The warning is improper along with the comment. The right thing is to inherit the pte marker when needed, or keep the dst pte empty. A vague guess is this happened by an accident when there's the prior patch to introduce src/dst vma into this helper during the uffd-wp feature got developed and I probably messed up in the rebase, since if we replace dst_vma with src_vma the warning & comment it all makes sense too. Hugetlb did exactly the right here (copy_hugetlb_page_range()). Fix the general path. Reproducer: https://github.com/xupengfe/syzkaller_logs/blob/main/221208_115556_copy_page_range/repro.c Bugzilla report: https://bugzilla.kernel.org/show_bug.cgi?id=216808 Link: https://lkml.kernel.org/r/20221214200453.1772655-1-peterx@redhat.com Link: https://lkml.kernel.org/r/20221214200453.1772655-2-peterx@redhat.com Fixes: c56d1b62cce8 ("mm/shmem: handle uffd-wp during fork()") Signed-off-by: Peter Xu Reported-by: Pengfei Xu Cc: Andrea Arcangeli Cc: David Hildenbrand Cc: "Huang, Ying" Cc: Miaohe Lin Cc: Nadav Amit Cc: # 5.19+ Signed-off-by: Andrew Morton --- mm/memory.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) --- a/mm/memory.c~mm-uffd-fix-pte-marker-when-fork-without-fork-event +++ a/mm/memory.c @@ -828,12 +828,8 @@ copy_nonpresent_pte(struct mm_struct *ds return -EBUSY; return -ENOENT; } else if (is_pte_marker_entry(entry)) { - /* - * We're copying the pgtable should only because dst_vma has - * uffd-wp enabled, do sanity check. - */ - WARN_ON_ONCE(!userfaultfd_wp(dst_vma)); - set_pte_at(dst_mm, addr, dst_pte, pte); + if (userfaultfd_wp(dst_vma)) + set_pte_at(dst_mm, addr, dst_pte, pte); return 0; } if (!userfaultfd_wp(dst_vma)) _ Patches currently in -mm which might be from peterx@redhat.com are mm-uffd-fix-pte-marker-when-fork-without-fork-event.patch mm-fix-a-few-rare-cases-of-using-swapin-error-pte-marker.patch