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From:   Hans-Peter Jansen <hpj@urpla.net>
To:     linux-nfs <linux-nfs@vger.kernel.org>,
        Anthony Joseph Messina <amessina@messinet.com>
Subject: Re: general protection fault,
 probably for non-canonical address in nfsd
Date:   Sun, 07 Jun 2020 19:44:35 +0200
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Am Sonntag, 7. Juni 2020, 18:01:55 CEST schrieb Anthony Joseph Messina:
> On Sunday, June 7, 2020 10:32:44 AM CDT Hans-Peter Jansen wrote:
> > Hi,
> > 
> > after upgrading the kernel from 5.6.11 to 5.6.14, we suffer from regular
> > crashes of nfsd here:
> > 
> > 2020-06-07T01:32:43.600306+02:00 server rpc.mountd[2664]: authenticated
> > mount request from 192.168.3.16:303 for /work (/work)
> > 2020-06-07T01:32:43.602594+02:00 server rpc.mountd[2664]: authenticated
> > mount request from 192.168.3.16:304 for /work/vmware (/work)
> > 2020-06-07T01:32:43.602971+02:00 server rpc.mountd[2664]: authenticated
> > mount request from 192.168.3.16:305 for /work/vSphere (/work)
> > 2020-06-07T01:32:43.606276+02:00 server kernel: [51901.089211] general
> > protection fault, probably for non-canonical address 0xb9159d506ba40000:
> > 0000 [#1] SMP PTI 2020-06-07T01:32:43.606284+02:00 server kernel:
> > [51901.089226] CPU: 1 PID: 3190 Comm: nfsd Tainted: G           O
> > 5.6.14-lp151.2-default #1 openSUSE Tumbleweed (unreleased)
> > 2020-06-07T01:32:43.606286+02:00 server kernel: [51901.089234] Hardware
> > name: System manufacturer System Product Name/P7F-E, BIOS 0906
> 
> I see similar issues in Fedora kernels 5.6.14 through 5.6.16
> https://bugzilla.redhat.com/show_bug.cgi?id=1839287
> 
> On the client I mount /home with sec=krb5p, and /mnt/koji with sec=krb5

Thanks for confirmation. 

Apart from the hassle with server reboots, this issue has some DOS potential, 
I'm afraid.

Cheers,
Pete