Re: [PATCH 5.4] NFSD: Force all NFSv4.2 COPY requests to be synchronous

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Dec 02, 2024 at 02:19:13PM +0000, Chuck Lever III wrote:
> 
> 
> > On Dec 2, 2024, at 4:09 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
> > 
> > On Wed, Nov 20, 2024 at 02:13:15PM -0500, cel@kernel.org wrote:
> >> From: Chuck Lever <chuck.lever@oracle.com>
> >> 
> >> [ Upstream commit 8d915bbf39266bb66082c1e4980e123883f19830 ]
> > 
> > What about kernel versions greater than 5.4?  Like 5.10, 5.15, 6.1, and
> > 6.6 for this change?  Shouldn't it also be needed there?
> 
> Good catch. My rationale is:
> 
> Asynchronous COPY offload is needed to implement NFSv4.2
> server-to-server COPY offload.
> 
> The upstream patches that address the CVE don't apply
> cleanly to linux-5.4.y. However, 5.4 kernels do not have
> NFSv4.2 server-to-server COPY offload, thus this change,
> which simply disables async COPY, has no user-visible
> impact. So I decided the easy, low-impact way to address
> the CVE for v5.4 was applying only this patch.
> 
> The newer LTS kernels do have server-to-server COPY offload,
> thus if this patch is applied, they would see a behavior
> regression whenever CONFIG_NFSD_V4_2_INTER_SSC is enabled.
> The upstream patches that address the CVE apply cleanly to
> these kernels, and I've sent those to stable@ already.
> 
> As these were separate patch series, there wasn't an
> obvious place to add a cover letter that explains this.

Ok, that's fine, we'll just leave this as-is, thanks!

greg k-h