Meng Zhu created MESOS-9144:
-------------------------------
Summary: Master handles authentication requests with strong
assumption thus can easily be overwhelmed.
Key: MESOS-9144
URL: https://issues.apache.org/jira/browse/MESOS-9144
Project: Mesos
Issue Type: Bug
Affects Versions: 1.6.1, 1.5.1
Reporter: Meng Zhu
In `Master::authenticate(const UPID& from, const UPID& pid)`, we have:
https://github.com/apache/mesos/blob/master/src/master/master.cpp#L9594
{code:c++}
if (authenticating.contains(pid)) {
LOG(INFO) << "Queuing up authentication request from " << pid
<< " because authentication is still in progress";
// Try to cancel the in progress authentication by discarding the
// future.
authenticating[pid].discard();
// Retry after the current authenticator session finishes.
authenticating[pid]
.onAny(defer(self(), &Self::authenticate, from, pid));
return;
}
{code}
Let's say the master is processing authentication request R1 (whose associating
future is held in `authenticating`). Now it receives another request R2 from
the same client (due to e.g. re-try), according to the above code logic, we
will (1) discard R1; (2) enqueue R2 as a callback which will be triggered when
R1 is discarded, and we will redo `:: authenticate` with R2.
Here the master assumes that R2 is the most current request. This is true in
the above example. However, this assumption could easily break when auth
requests come faster than they are discarded. If we have 3 requests (R1, R2,
R3) in the event queue, then we could trigger `::authenticate` SIX times in
total, once for R1, twice for R2 and three times for R3. This grows in
quadratic to the number of enqueued requests and the master will be overwhelmed.
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