x/vulndb: potential Go vuln in github.com/hashicorp/yamux

[lattwood]

Acknowledgement

• The maintainer(s) of the affected project have already been made aware of this vulnerability.

Description

The default values for Session.config.KeepAliveInterval and Session.config.ConnectionWriteTimeout of 30s and 10s create the possibility for timed out writes that most aren't handling in their readers.

Calls to Stream.Read on one side of a connection will hang until the underlying Session is closed if the corresponding Stream.Write call on the other side it's waiting for returns with ErrConnectionWriteTimeout. This happens in the case of network congestion between the two sides.

If you keep Session.sendCh full (fixed capacity of 64) for ConnectionWriteTimeout, but for less than the KeepAliveInterval + ConnectionWriteTimeout (which would kill the Session), Stream.Write will return ErrConnectionWriteTimeout. The state of the underlying Session or Stream is not modified. When this happens, the other side's Stream.Read call that's waiting for that write will never return because there's no timeout for this edge-case.

Since no keep alive timed out, you can continue to use the Session once the network congestion is resolved, but that Stream.Read call will only return when the Session closes or the response shows up. Since the write call on the other side timed out the call to Stream.Read will never return.

Any conditions that cause network writes to stall for 10-30 seconds can trigger this Denial of Service- extremely high CPU contention on either side of the connection, BGP reconvergence, etc. To resolve the Denial of Service issue, you have to re-establish the connections, which will usually require a hard restart of the service on either end of the connection.

Affected Modules, Packages, Versions and Symbols

Module: github.com/hashicorp/yamux
Package: github.com/hashicorp/yamux
Versions:
  - Introduced: 0.1.0
  - Fixed: N/A
Symbols:
  - DefaultConfig
  - Server
  - Client

CVE/GHSA ID

No response

Fix Commit or Pull Request

hashicorp/yamux#143

References

• pending allocations stuck in pending state after adoption by a new deployment hashicorp/nomad#23305 (original discovery, had no idea about root cause at this point)
• DefaultConfig has dangerous defaults causing hung Reads hashicorp/yamux#142 (bug report against library)

Additional information

No response

[dduzgun-security]

Hi @lattwood, really appreciate all the work and details here.
Since HashiCorp is a CNA, we are responsible of evaluating, releasing and then issuing vulnerabilities that will get through the public vulnerability databases once published. We'll assist and help on the CVE submission part.