From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lithops.sigma-star.at (lithops.sigma-star.at [195.201.40.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 269DD1700; Tue, 5 Dec 2023 01:23:00 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by lithops.sigma-star.at (Postfix) with ESMTP id 8C01E6435FE5; Tue, 5 Dec 2023 10:22:57 +0100 (CET) Received: from lithops.sigma-star.at ([127.0.0.1]) by localhost (lithops.sigma-star.at [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id uoAS2t4MeggD; Tue, 5 Dec 2023 10:22:57 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by lithops.sigma-star.at (Postfix) with ESMTP id 20FE66436003; Tue, 5 Dec 2023 10:22:57 +0100 (CET) Received: from lithops.sigma-star.at ([127.0.0.1]) by localhost (lithops.sigma-star.at [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id 18FfdAYlCNUA; Tue, 5 Dec 2023 10:22:57 +0100 (CET) Received: from lithops.sigma-star.at (lithops.sigma-star.at [195.201.40.130]) by lithops.sigma-star.at (Postfix) with ESMTP id ED2F16435FE5; Tue, 5 Dec 2023 10:22:56 +0100 (CET) Date: Tue, 5 Dec 2023 10:22:56 +0100 (CET) From: Richard Weinberger To: Miquel Raynal Cc: Mark Brown , linux-spi , Thomas Petazzoni , Ryan Wanner , Ronald Wahl , David Laight , Nicolas Ferre , Claudiu Beznea , Alexandre Belloni , linux-arm-kernel , stable Message-ID: <1788823860.72909.1701768176780.JavaMail.zimbra@nod.at> In-Reply-To: <20231205083102.16946-1-miquel.raynal@bootlin.com> References: <20231205083102.16946-1-miquel.raynal@bootlin.com> Subject: Re: [PATCH] spi: atmel: Prevent spi transfers from being killed Precedence: bulk X-Mailing-List: linux-spi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Mailer: Zimbra 8.8.12_GA_3807 (ZimbraWebClient - FF97 (Linux)/8.8.12_GA_3809) Thread-Topic: atmel: Prevent spi transfers from being killed Thread-Index: Quru2fECYqrOtaULSEivNT3zKaeElw== ----- Urspr=C3=BCngliche Mail ----- > Von: "Miquel Raynal" > All being well, it was reported that JFFS2 was showing a splat when > interrupting a transfer. After some more debate about whether JFFS2 > should be fixed and how, it was also pointed out that the whole > consistency of the filesystem in case of parallel I/O would be > compromised. Changing JFFS2 behavior would in theory be possible but > nobody has the energy and time and knowledge to do this now, so better > prevent spi transfers to be interrupted by the user. Well, it's not really an JFFS2 issue. The real problem is, that with the said change anyone can abort an IO. Usually file systems assume that an IO can only fail in fatal situations. That's why UBIFS, for example, switches immediately to read-only mode. So, an unprivileged user can force UBIFS into read-only mode, which is a local DoS attack vector. JFFS2, on the other hand, dies a different death. If you abort one IO, another IO path can still be active and will violate the order of written data. Long story short, aborting pure user inflicted IO is fine. This is the "dd" use case. But as soon a filesystem is on top, things get complicated. Maybe it is possible to teach the SPI subsystem whether an IO comes from sp= idev or the kernel itself? Thanks, //richard 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 65A5AC4167B for ; Tue, 5 Dec 2023 09:23:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Subject:References: In-Reply-To:Message-ID:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=6J0kfHyRbS6NJHSeRg/z64Ollh5H1+29c/V6rZNp/iA=; b=3g34WqvTR3W0Zr rhuUJNFDw/EvaDdq9SXCisq6WrqjDsd5oknfgo/N0ukcqjGlY8AZbYzJZYQ+mtEZ6QAyepqedfOMq 1rzVR5I/hUagLRiyauZ1CzSLZEtYXUt2//Blm97rK+skjv5nHjEPkUsvLu2ZV84Tjjmyn92TD2xf7 wbCLozmn+ymFFGQXWmPGHMN4pqKblg3st+wPtPsmNB3Yex/xJ8yPhmlqeG2fiP6ro9k38LoKG0Mum zlaSDZr081ujEt8iKA/G2slQBfxkiAlKbIZemXXotSLCmlFKY0v2Ot6cIWRdfUEjkBFCqJu/peTdI HREqHfazUyOMMuTeLnTA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1rARe4-006mgB-1O; Tue, 05 Dec 2023 09:23:12 +0000 Received: from lithops.sigma-star.at ([195.201.40.130]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1rARe0-006mVX-2d for linux-arm-kernel@lists.infradead.org; Tue, 05 Dec 2023 09:23:10 +0000 Received: from localhost (localhost [127.0.0.1]) by lithops.sigma-star.at (Postfix) with ESMTP id 8C01E6435FE5; Tue, 5 Dec 2023 10:22:57 +0100 (CET) Received: from lithops.sigma-star.at ([127.0.0.1]) by localhost (lithops.sigma-star.at [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id uoAS2t4MeggD; Tue, 5 Dec 2023 10:22:57 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by lithops.sigma-star.at (Postfix) with ESMTP id 20FE66436003; Tue, 5 Dec 2023 10:22:57 +0100 (CET) Received: from lithops.sigma-star.at ([127.0.0.1]) by localhost (lithops.sigma-star.at [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id 18FfdAYlCNUA; Tue, 5 Dec 2023 10:22:57 +0100 (CET) Received: from lithops.sigma-star.at (lithops.sigma-star.at [195.201.40.130]) by lithops.sigma-star.at (Postfix) with ESMTP id ED2F16435FE5; Tue, 5 Dec 2023 10:22:56 +0100 (CET) Date: Tue, 5 Dec 2023 10:22:56 +0100 (CET) From: Richard Weinberger To: Miquel Raynal Message-ID: <1788823860.72909.1701768176780.JavaMail.zimbra@nod.at> In-Reply-To: <20231205083102.16946-1-miquel.raynal@bootlin.com> References: <20231205083102.16946-1-miquel.raynal@bootlin.com> Subject: Re: [PATCH] spi: atmel: Prevent spi transfers from being killed MIME-Version: 1.0 X-Originating-IP: [195.201.40.130] X-Mailer: Zimbra 8.8.12_GA_3807 (ZimbraWebClient - FF97 (Linux)/8.8.12_GA_3809) Thread-Topic: atmel: Prevent spi transfers from being killed Thread-Index: Quru2fECYqrOtaULSEivNT3zKaeElw== X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231205_012309_016929_5F0F145B X-CRM114-Status: UNSURE ( 9.92 ) X-CRM114-Notice: Please train this message. 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