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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 BD519CD6E55 for ; Mon, 1 Jun 2026 20:25:18 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4gTlnn1wtmz2ydQ; Tue, 02 Jun 2026 06:25:17 +1000 (AEST) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip="2001:8b0:10b:1236::1" ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1780345517; cv=none; b=T0kMQmYBQWMh+t2UNMv3tpRi8JYeQo0qc77FUqTuStjkq8CatwTcsT1ZlVnsXwElAUOMYXwC6yv40zdOAYyxxOSJrzvYjp/YlTV5H5x5UzCeDTeoFuRpxQKZKmL8baglHv0Uf9vlTzQzc5swTj7wKC23ErF0l6YP0XnKq+t0HUT0CmJ+DkNsJkAbLts63/2iZj9162ux7BO0/WIRED3ZvTqYcW4NMzC8hsWXXE1jhpvwWh9QWjZGbWKMIkyS4T3Z/xrH6RNZNuTPmCu6eGcng/fwM75Zr0Jdx0Ticad1tKvd6AyCvnRnv2Mu4f+r1f3HW/aBaW0s3Zz821F5Gpfa/g== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1780345517; c=relaxed/relaxed; bh=6/5W0G6Gs1Q9GB3IxcldPERQvThA7tz7U249bqa4a9U=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=kMpyS3l8E1IDG4+rk1F9QduYpZZpdnneUCLUAbBzLLUpcx8aBOX4JMV8dtexMIPrw1BmAEiMI/l0rrrRTshzYRYRYmHn0oCc5dZFjgTGEwIvJJrmLpJBUeVbTvaoHpiCDR3I97VBYvmvnYA/BZHm9ponLboT1+yk5k8e2O7yjDNbwa0YxVABYuRmsRu/k7AVIYk/nudhFpLl+PU8wX3ICpD3/5IEuKUeKu9q6/RSsK8ZmF5P2MM6xP0iZLh7lVVZngZ3nMm/BLUBQoOdJiJsQbgNJI4s2HwEIFNI2xAXTQ+9K5k2v6DBhsg+2MDnZWQsssBJrDSRjtvE6q0ws4jkgg== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=infradead.org; dkim=pass (2048-bit key; secure) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=casper.20170209 header.b=JD/rgItE; dkim-atps=neutral; spf=pass (client-ip=2001:8b0:10b:1236::1; helo=casper.infradead.org; envelope-from=willy@infradead.org; receiver=lists.ozlabs.org) smtp.mailfrom=infradead.org Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; secure) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=casper.20170209 header.b=JD/rgItE; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=infradead.org (client-ip=2001:8b0:10b:1236::1; helo=casper.infradead.org; envelope-from=willy@infradead.org; receiver=lists.ozlabs.org) Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4gTlng3BS1z2yT0 for ; Tue, 02 Jun 2026 06:25:10 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=6/5W0G6Gs1Q9GB3IxcldPERQvThA7tz7U249bqa4a9U=; b=JD/rgItEItTF3waKZU0fyhZfOO p6KhOF2dIKsWbBlXDH6Szda6v6pwxYE0KSLQ6p9Jvu4aC0kMd1Jp91bHbXXGW1JY4kLAuzDZFSXs9 P7bQk5/xrqJRa6GrGWdxnMhnM9cOr/Mh7DhOreUlDgBnF2TcRdtGfQbRd9WsBVDwHFqfKKNmW2p+o Eq81r5ZCto6v0j62Ti/4LX0nmYsBAqhcbZ6JenvK3VL8pcuJJabuzAf2wJL1ohACsCSDs/sp5+nbD m2tuZulS6JhmLQAZ2oWemvoJrOfuaHp1Sctzmp2YTWfFeramTBO8sylg/IQVtL1hc2i3NQH4Kt9qQ +ovW+CfA==; Received: from willy by casper.infradead.org with local (Exim 4.99.1 #2 (Red Hat Linux)) id 1wU9Av-00000000iHG-2DOC; Mon, 01 Jun 2026 20:23:53 +0000 Date: Mon, 1 Jun 2026 21:23:53 +0100 From: Matthew Wilcox To: David Laight Cc: Kees Cook , Luis Chamberlain , Pengpeng Hou , stable@vger.kernel.org, Petr Pavlu , Richard Weinberger , Anton Ivanov , Johannes Berg , "Rafael J. Wysocki" , Len Brown , Corey Minyard , Gabriel Somlo , "Michael S. Tsirkin" , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Simona Vetter , Bart Van Assche , Jason Gunthorpe , Leon Romanovsky , Laurent Pinchart , Hans de Goede , Mauro Carvalho Chehab , Bjorn Helgaas , Hannes Reinecke , "James E.J. Bottomley" , "Martin K. Petersen" , Daniel Lezcano , Zhang Rui , Lukasz Luba , Greg Kroah-Hartman , Jiri Slaby , Alan Stern , Jason Wang , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , Jason Baron , Jim Cromie , Tiwei Bie , Benjamin Berg , Ilpo =?iso-8859-1?Q?J=E4rvinen?= , "David E. Box" , "Maciej W. Rozycki" , Srinivas Pandruvada , Peter Zijlstra , Heiko Carstens , Vasily Gorbik , Sean Christopherson , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Vinod Koul , Frank Li , Daniel Gomez , Sami Tolvanen , Aaron Tomlin , Alexander Potapenko , Marco Elver , Dmitry Vyukov , Andrew Morton , John Johansen , Paul Moore , James Morris , "Serge E. Hallyn" , Andy Shevchenko , Georgia Garcia , kvm@vger.kernel.org, dmaengine@vger.kernel.org, linux-modules@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, apparmor@lists.ubuntu.com, linux-security-module@vger.kernel.org, linux-um@lists.infradead.org, linux-acpi@vger.kernel.org, openipmi-developer@lists.sourceforge.net, qemu-devel@nongnu.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, linux-pci@vger.kernel.org, linux-scsi@vger.kernel.org, linux-pm@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-serial@vger.kernel.org, linux-usb@vger.kernel.org, usb-storage@lists.one-eyed-alien.net, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, netdev@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH 01/11] params: bound array element output to the caller's page buffer Message-ID: References: <20260521133315.work.845-kees@kernel.org> <20260521133326.2465264-1-kees@kernel.org> <20260521174631.71a06440@pumpkin> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260521174631.71a06440@pumpkin> On Thu, May 21, 2026 at 05:46:31PM +0100, David Laight wrote: > On Thu, 21 May 2026 06:33:14 -0700 > Kees Cook wrote: > > Collect each element into a temporary PAGE_SIZE buffer first and then > > copy only the remaining space into the caller's page buffer. > > Should this be using a 4k buffer on all architectures? > Initially perhaps just using a different name for the constant until > all the associated PAGE_SIZE limits have been removed. If we're acually going to think about this, even 4KiB is too big. An 80x25 terminal is 2000 bytes (assuming no utf8), so 4KiB is two entire screenfuls. Limiting to 2048 would seem reasonable to me.