From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux admin Subject: Re: decruft the vmalloc API Date: Wed, 8 Apr 2020 17:03:24 +0100 Message-ID: <20200408160324.GS25745@shell.armlinux.org.uk> References: <20200408115926.1467567-1-hch@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20200408115926.1467567-1-hch@lst.de> Sender: linux-kernel-owner@vger.kernel.org To: Christoph Hellwig Cc: Andrew Morton , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Wei Liu , x86@kernel.org, David Airlie , Daniel Vetter , Laura Abbott , Sumit Semwal , Sakari Ailus , Minchan Kim , Nitin Gupta , Christophe Leroy , linux-arch@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-s390@vger.kernel.org, Peter Zijlstra , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org List-Id: linux-arch.vger.kernel.org On Wed, Apr 08, 2020 at 01:58:58PM +0200, Christoph Hellwig wrote: > Hi all, > > Peter noticed that with some dumb luck you can toast the kernel address > space with exported vmalloc symbols. > > I used this as an opportunity to decruft the vmalloc.c API and make it > much more systematic. This also removes any chance to create vmalloc > mappings outside the designated areas or using executable permissions > from modules. Besides that it removes more than 300 lines of code. I haven't read all your patches yet. Have you tested it on 32-bit ARM, where the module area is located _below_ PAGE_OFFSET and outside of the vmalloc area? -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 10.2Mbps down 587kbps up From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from pandora.armlinux.org.uk ([78.32.30.218]:58758 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729686AbgDHQEK (ORCPT ); Wed, 8 Apr 2020 12:04:10 -0400 Date: Wed, 8 Apr 2020 17:03:24 +0100 From: Russell King - ARM Linux admin Subject: Re: decruft the vmalloc API Message-ID: <20200408160324.GS25745@shell.armlinux.org.uk> References: <20200408115926.1467567-1-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200408115926.1467567-1-hch@lst.de> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Christoph Hellwig Cc: Andrew Morton , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Wei Liu , x86@kernel.org, David Airlie , Daniel Vetter , Laura Abbott , Sumit Semwal , Sakari Ailus , Minchan Kim , Nitin Gupta , Christophe Leroy , linux-arch@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-s390@vger.kernel.org, Peter Zijlstra , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, bpf@vger.kernel.org, Robin Murphy , linux-arm-kernel@lists.infradead.org Message-ID: <20200408160324.7-FEU9MWXnpQxL1bRTbQBFVykWPWJI-1HniB6_vXTGQ@z> On Wed, Apr 08, 2020 at 01:58:58PM +0200, Christoph Hellwig wrote: > Hi all, > > Peter noticed that with some dumb luck you can toast the kernel address > space with exported vmalloc symbols. > > I used this as an opportunity to decruft the vmalloc.c API and make it > much more systematic. This also removes any chance to create vmalloc > mappings outside the designated areas or using executable permissions > from modules. Besides that it removes more than 300 lines of code. I haven't read all your patches yet. Have you tested it on 32-bit ARM, where the module area is located _below_ PAGE_OFFSET and outside of the vmalloc area? -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 10.2Mbps down 587kbps up