linux-kernel - Re: [PATCH] mm/vmalloc: Sanitize __get_vm

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Date:   Fri, 17 Apr 2020 15:14:24 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc:     Christoph Hellwig <hch@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org, jroedel@...e.de,
        vbabka@...e.cz, urezki@...il.com,
        Thomas Gleixner <tglx@...utronix.de>,
        Olof Johansson <olof@...om.net>,
        Mauro Carvalho Chehab <mchehab@...nel.org>
Subject: Re: [PATCH] mm/vmalloc: Sanitize __get_vm_area() arguments

On Fri, Apr 17, 2020 at 03:57:35PM +0300, Sakari Ailus wrote:
> Hi Christoph,
> 
> On Mon, Apr 06, 2020 at 06:01:55AM -0700, Christoph Hellwig wrote:
> > On Fri, Apr 03, 2020 at 06:32:53PM +0200, Peter Zijlstra wrote:
> > > 
> > > __get_vm_area() is an exported symbol, make sure the callers stay in
> > > the expected memory range. When calling this function with memory
> > > ranges outside of the VMALLOC range *bad* things can happen.
> > > 
> > > (I noticed this when I managed to corrupt the kernel text by accident)
> > 
> > Maybe it is time to unexport it?  There are only two users:
> > 
> >  - staging/media/ipu3 really should be using vmap.  And given that it
> >    is a staging driver it really doesn't matter anyway if we break it.
> 
> It's not very polite to suggest breaking other people's drivers for such a
> small matter, staging or not. That'd be bound to break kernel compilation
> for a lot of people, if for nothing else.
> 
> Anyway, thanks for cc'ing me. I agree with suggestion and I'll submit a
> patch to address it.

Already done, see:

  https://lkml.kernel.org/r/20200414131348.444715-5-hch@lst.de