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Message-ID: <ZEwPscQu68kx32zF@mit.edu>
Date: Fri, 28 Apr 2023 14:25:53 -0400
From: "Theodore Ts'o" <tytso@....edu>
To: Jason Gunthorpe <jgg@...dia.com>
Cc: David Hildenbrand <david@...hat.com>,
Lorenzo Stoakes <lstoakes@...il.com>, linux-mm@...ck.org,
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Subject: Re: [PATCH v5] mm/gup: disallow GUP writing to file-backed mappings
by default
On Fri, Apr 28, 2023 at 11:35:32AM -0300, Jason Gunthorpe wrote:
>
> It has been years now, I think we need to admit a fix is still years
> away. Blocking the security problem may even motivate more people to
> work on a fix.
Do we think we can still trigger a kernel crash, or maybe even some
more exciting like an arbitrary buffer overrun, via the
process_vm_writev(2) system call into a file-backed mmap'ed region?
Maybe if someone can come up with an easy-to-expliot security proof of
aconcept, that doesn't require special RDMA hardware or some special
libvirt setup, we could finally get motivation to get it fixed, or at
least blocked? :-)
We've only been talking about it for years, after all...
- Ted
> Security is the primary case where we have historically closed uAPI
> items.
>
> Jason
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