Juergen Gross fe415186b4 xen/console: harden hvc_xen against event channel storms
The Xen console driver is still vulnerable for an attack via excessive
number of events sent by the backend. Fix that by using a lateeoi event
channel.

For the normal domU initial console this requires the introduction of
bind_evtchn_to_irq_lateeoi() as there is no xenbus device available
at the time the event channel is bound to the irq.

As the decision whether an interrupt was spurious or not requires to
test for bytes having been read from the backend, move sending the
event into the if statement, as sending an event without having found
any bytes to be read is making no sense at all.

This is part of XSA-391

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---
V2:
- slightly adapt spurious irq detection (Jan Beulich)
V3:
- fix spurious irq detection (Jan Beulich)
2021-12-16 08:24:08 +01:00
2021-12-15 10:52:01 -08:00
2021-12-11 09:25:07 -08:00
2021-11-13 15:32:30 -08:00
2021-12-13 14:34:22 -08:00
2021-12-10 11:43:00 -08:00
2021-12-12 14:53:01 -08:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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