envoyproxy/envoy

Connection Limit filter reporting 18 quintillion active connections

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#22,127 opened on Jul 12, 2022

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area/ratelimitbughelp wanted

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Description

We have observed that Envoy with the Connection Limit Filter configured, at some point will report 2**64 active connections for the metric envoy.connection_limit.<listener>.active_connections.

This seems suspicious and could be indicative of some integer overflow.

This did not result in a crash, but did result in some connections being limited when it was not intended.

We configured the filter with a max_connections of 56000 and delay of 500ms

Contributor guide

Research direction
Inspect the Connection Limit filter code in Envoy, specifically the tracking of active connections. Look for integer overflow issues when incrementing/decrementing the counter, possibly related to using uint64 t without proper handling of overflow. Check if the counter is correctly reset or bounded.
Tech stack
cpp
Domain
backendapiinfrastructure
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C++Envoy
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40