linux-kernel - Re: decruft the vmalloc API

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Message-ID: <20200408160324.GS25745@shell.armlinux.org.uk>
Date:   Wed, 8 Apr 2020 17:03:24 +0100
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Christoph Hellwig <hch@....de>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, x86@...nel.org,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Laura Abbott <labbott@...hat.com>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Minchan Kim <minchan@...nel.org>,
        Nitin Gupta <ngupta@...are.org>,
        Christophe Leroy <christophe.leroy@....fr>,
        linux-arch@...r.kernel.org, linux-hyperv@...r.kernel.org,
        linux-s390@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linaro-mm-sig@...ts.linaro.org,
        linux-mm@...ck.org, iommu@...ts.linux-foundation.org,
        bpf@...r.kernel.org, Robin Murphy <robin.murphy@....com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: decruft the vmalloc API

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/
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