[Bug 960276] Re: a bad AMI can hang an entire compute node

[Adam Gandelman]

We've been carrying a nova patch to resolve a possible DoS in Bug
#832507 ( libvirt-use-console-pipe.patch )  I've confirmed that this
patch introduces a deadlock somewhere when the serial console gets
spammed.  'dd if=/dev/urandom of=/dev/ttyS0 bs=1024 count=1500'  from
within the instance is enough to basically lock nova-compute until the
KVM process is killed or nova-compute restarted.

We either need to fix this patch ASAP or back it out in favor of a
different solution for the original  Bug #832507.  This patch
constitutes the biggest delta we maintain across any Openstack component
and maintaining it so far has required a great deal of effort.  The
regression its introduces is worse than the original bug, IMO.

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https://bugs.launchpad.net/bugs/960276

Title:
  a bad AMI can hang an entire compute node

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