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 491E0C43219 for ; Tue, 22 Mar 2022 21:42:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236037AbiCVVnr (ORCPT ); Tue, 22 Mar 2022 17:43:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50584 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236161AbiCVVnn (ORCPT ); Tue, 22 Mar 2022 17:43:43 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 199285F258 for ; Tue, 22 Mar 2022 14:42:12 -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 B900AB81DB3 for ; Tue, 22 Mar 2022 21:42:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7207CC340EC; Tue, 22 Mar 2022 21:42:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1647985329; bh=fBURoQBf/NowRAcjUkoyhi0STImz+EpOKIqpkfRNgXY=; h=Date:To:From:In-Reply-To:Subject:From; b=FlYP2pY1YK9tZkBy5h0DoAbInaMf/yVsWIYfUyzfn4cF3vmwcpgIGT/ig5W5gwrr6 ZJf5skhU194M5+cNoz/vd7JNrk/kzUemIb7lax6/bleB+Np26O/3dv4wtsIx51hfio U2rf9OQ5bYaz/vTL1VzlMbFyozyycBD9Wwi1VdAU= Date: Tue, 22 Mar 2022 14:42:08 -0700 To: ziy@nvidia.com, rientjes@google.com, peterx@redhat.com, mike.kravetz@oracle.com, lars.persson@axis.com, kirill.shutemov@linux.intel.com, fam.zheng@bytedance.com, duanxiongchun@bytedance.com, axelrasmussen@google.com, songmuchun@bytedance.com, akpm@linux-foundation.org, patches@lists.linux.dev, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org From: Andrew Morton In-Reply-To: <20220322143803.04a5e59a07e48284f196a2f9@linux-foundation.org> Subject: [patch 071/227] mm: userfaultfd: fix missing cache flush in mcopy_atomic_pte() and __mcopy_atomic() Message-Id: <20220322214209.7207CC340EC@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Muchun Song Subject: mm: userfaultfd: fix missing cache flush in mcopy_atomic_pte() and __mcopy_atomic() userfaultfd calls mcopy_atomic_pte() and __mcopy_atomic() which do not do any cache flushing for the target page. Then the target page will be mapped to the user space with a different address (user address), which might have an alias issue with the kernel address used to copy the data from the user to. Fix this by insert flush_dcache_page() after copy_from_user() succeeds. Link: https://lkml.kernel.org/r/20220210123058.79206-7-songmuchun@bytedance.com Fixes: b6ebaedb4cb1 ("userfaultfd: avoid mmap_sem read recursion in mcopy_atomic") Fixes: c1a4de99fada ("userfaultfd: mcopy_atomic|mfill_zeropage: UFFDIO_COPY|UFFDIO_ZEROPAGE preparation") Signed-off-by: Muchun Song Cc: Axel Rasmussen Cc: David Rientjes Cc: Fam Zheng Cc: Kirill A. Shutemov Cc: Lars Persson Cc: Mike Kravetz Cc: Peter Xu Cc: Xiongchun Duan Cc: Zi Yan Signed-off-by: Andrew Morton --- mm/userfaultfd.c | 3 +++ 1 file changed, 3 insertions(+) --- a/mm/userfaultfd.c~mm-userfaultfd-fix-missing-cache-flush-in-mcopy_atomic_pte-and-__mcopy_atomic +++ a/mm/userfaultfd.c @@ -150,6 +150,8 @@ static int mcopy_atomic_pte(struct mm_st /* don't free the page */ goto out; } + + flush_dcache_page(page); } else { page = *pagep; *pagep = NULL; @@ -625,6 +627,7 @@ retry: err = -EFAULT; goto out; } + flush_dcache_page(page); goto retry; } else BUG_ON(page); _