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 C3B10C433FE for ; Mon, 3 Oct 2022 09:11:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231287AbiJCJLu (ORCPT ); Mon, 3 Oct 2022 05:11:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51682 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231267AbiJCJLa (ORCPT ); Mon, 3 Oct 2022 05:11:30 -0400 Received: from mail-qt1-f169.google.com (mail-qt1-f169.google.com [209.85.160.169]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90CC218E27; Mon, 3 Oct 2022 02:09:26 -0700 (PDT) Received: by mail-qt1-f169.google.com with SMTP id f26so5979307qto.11; Mon, 03 Oct 2022 02:09:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date; bh=trTfDJMo708QkzlgeeP2MRgqzTNqQkR+d0aIDLbnGMQ=; b=CM73RZ3xNKNAiwdHoewawhkDzR+4Ar8kMGAbhAphtIcAKAPRenXHwAmsKWivlq4jT8 2glXVxYhxwkQBE84n+vnUo1Z3xPEALnmprsckEJh6t+Lmg/OLT/1dRMsExoWeHL3XKLY bnKdjAbeP+OWIyDjQnDMsI96AhRIozudMYoX85Dd969TYNLKcSQH6TEUOmqR7M0pTFmV 4hYjLX3nmhODMj2NRmZZWEz9PkzTHe899oDtSW3KygSAS4FqCHR0u3mYqf2qbHJzWgqH bsaZGGFto9UgEQeZmUUpcTV3kBmqxu/o0RRJEpobCYkaFeZgjSgWhI0fdQxyuAMSgkt4 tc/Q== X-Gm-Message-State: ACrzQf3YlRX4lw+BbYL2jX19yYGmNCJqvbzXtNDsJGd2pq7Frwh1AXSF 3eRuRPTSaezlfwBF7GjdMEljN1xM03mQuA== X-Google-Smtp-Source: AMsMyM6Lu+98pbw7nZyM3mtVAOOiFgdp408U9x6rwhHYOtp9U6afIsQxpCHEzlUcQ5o7ScH9SizVfQ== X-Received: by 2002:a05:622a:14d0:b0:35c:c205:7d25 with SMTP id u16-20020a05622a14d000b0035cc2057d25mr15135703qtx.5.1664788165084; Mon, 03 Oct 2022 02:09:25 -0700 (PDT) Received: from mail-yb1-f177.google.com (mail-yb1-f177.google.com. [209.85.219.177]) by smtp.gmail.com with ESMTPSA id g9-20020a05620a40c900b006bbe6e89bdcsm11202173qko.31.2022.10.03.02.09.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 03 Oct 2022 02:09:24 -0700 (PDT) Received: by mail-yb1-f177.google.com with SMTP id 207so9018391ybn.1; Mon, 03 Oct 2022 02:09:24 -0700 (PDT) X-Received: by 2002:a05:6902:45:b0:6ae:ce15:a08d with SMTP id m5-20020a056902004500b006aece15a08dmr18338529ybh.380.1664788164575; Mon, 03 Oct 2022 02:09:24 -0700 (PDT) MIME-Version: 1.0 References: <20221003070724.490989164@linuxfoundation.org> <20221003070726.658463729@linuxfoundation.org> In-Reply-To: <20221003070726.658463729@linuxfoundation.org> From: Geert Uytterhoeven Date: Mon, 3 Oct 2022 11:09:12 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 5.19 089/101] dont use __kernel_write() on kmap_local_page() To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Al Viro , Sasha Levin Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Greg, On Mon, Oct 3, 2022 at 9:28 AM Greg Kroah-Hartman wrote: > From: Al Viro > > [ Upstream commit 06bbaa6dc53cb72040db952053432541acb9adc7 ] > > passing kmap_local_page() result to __kernel_write() is unsafe - > random ->write_iter() might (and 9p one does) get unhappy when > passed ITER_KVEC with pointer that came from kmap_local_page(). > > Fix by providing a variant of __kernel_write() that takes an iov_iter > from caller (__kernel_write() becomes a trivial wrapper) and adding > dump_emit_page() that parallels dump_emit(), except that instead of > __kernel_write() it uses __kernel_write_iter() with ITER_BVEC source. > > Fixes: 3159ed57792b "fs/coredump: use kmap_local_page()" > Signed-off-by: Al Viro > Signed-off-by: Sasha Levin This will need a follow-up patch, which I have just posted[1], to not break the build if CONFIG_ELF_CORE is not set. [1] https://lore.kernel.org/20221003090657.2053236-1-geert@linux-m68k.org Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds