linux-kernel - Re: CVE-2024-57937: mm: reinstate ability to map write-sealed memfd mappings read-only

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Message-ID: <2025012228-tarot-garland-80c1@gregkh>
Date: Wed, 22 Jan 2025 13:36:32 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: cve@...nel.org, linux-kernel@...r.kernel.org,
	linux-cve-announce@...r.kernel.org
Subject: Re: CVE-2024-57937: mm: reinstate ability to map write-sealed memfd
 mappings read-only

On Wed, Jan 22, 2025 at 11:51:10AM +0000, Lorenzo Stoakes wrote:
> On Sun, Sep 16, 2001 at 11:00:00PM +0000, Greg Kroah-Hartman wrote:
> > Description
> > ===========
> >
> > In the Linux kernel, the following vulnerability has been resolved:
> >
> > mm: reinstate ability to map write-sealed memfd mappings read-only
> 
> Hi Greg,
> 
> This is not a vulnerability and I don't see how it could possibly be
> exploited. So unless somebody can suggest a means by which it could be, I
> suggest this CVE should be dropped.
> 
> Thanks, Lorenzo
> 
> >
> > Patch series "mm: reinstate ability to map write-sealed memfd mappings
> > read-only".
> >
> > In commit 158978945f31 ("mm: perform the mapping_map_writable() check
> > after call_mmap()") (and preceding changes in the same series) it became
> > possible to mmap() F_SEAL_WRITE sealed memfd mappings read-only.

I thought the ability to mmap a sealed memfd mapping as read-only that
didn't want to be mmaped that way was a "vulnerability fix".

If you don't think so, then that's fine, we'll be glad to revoke this,
just let us know.

thanks,

greg k-h