Re: Possible bug? DOM-U network stopped working after fatal error reported in DOM0

[Juergen Gross <jgross@xxxxxxxx>]

On 18.12.21 19:35, G.R. wrote:
> Hi all,
>
> I ran into the following error report in the DOM0 kernel after a recent upgrade:
> [  501.840816] vif vif-1-0 vif1.0: Cross page boundary, txp->offset:
> 2872, size: 1460
> [  501.840828] vif vif-1-0 vif1.0: fatal error; disabling device
The dom0 network backend has detected an inconsistency in the data
received from the domU's frontend. In this case a request's memory
buffer crossed a page boundary, which is not allowed.

There has been a recent change in the xen netback driver to stop the
interface in such conditions, as such invalid requests are regarded to
be malicious and might lead to crashes in dom0.

So this issue should be reported to FreeBSD maintainers in order to
have the Xen netfornt driver fixed there.

> [  501.841076] xenbr0: port 2(vif1.0) entered disabled state
> Once this error happens, the DOM-U behind this vif is no-longer
> accessible. And recreating the same DOM-U does not fix the problem.
> Only a reboot on the physical host machine helps.
>
> The problem showed up after a recent upgrade on the DOM-U OS from
> FreeNAS 11.3 to TrueNAS 12.0U7 and breaks the iSCSI service while
> leaving other services like NFS intact.
> The underlying OS for the NAS is FreeBSD, version 11.3 and 12.2 respectively.
> So far I have tried the following combos:
> - Linux 4.19 DOM0 + XEN 4.8 + FreeBSD 11.3 DOM-U: Good
> - Linux 4.19 DOM0 + XEN 4.8 + FreeBSD 12.2 DOM-U: Regressed
> - Linux 5.10 DOM0 + XEN 4.8 + FreeBSD 12.2 DOM-U: Regressed
> - Linux 5.10 DOM0 + XEN 4.11 + FreeBSD 12.2 DOM-U: Regressed
This information (especially the FreeBSD version affected) is
probably important for the FreeBSD maintainers.

> I plan to try out the XEN 4.14 version which is the latest I can get
> from the distro (Debian).
> If that still does not fix the problem, I would build the 4.16 version
> from source as my last resort.
Xen is NOT to blame here.


Juergen

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