bug: hooks without timeout cause Exec() to hang indefinitely

[Chennamma-Hotkar]

Description

In pkg/unikontainers/utils.go, executeHook() only sets a context
timeout when hook.Timeout is explicitly set in the OCI spec:

if hook.Timeout != nil && *hook.Timeout > 0 {
    ctx, cancel = context.WithTimeout(...)
}

The OCI spec defines Timeout as optional (*int, omitempty).
When absent, context.Background() is used — which never cancels.

A hook process that hangs forever will block executeHooksConcurrently()
because wg.Wait() never returns, errChan never closes, and
for err := range errChan blocks forever. The container never starts
and no error or warning is logged.

The comment on line 312 says "otherwise use global config timeout"
but no global timeout is implemented in UruncConfig.

System info

• Urunc version: 0.7.0-154fc9e
• Arch: x86_64
• VMM: any
• Unikernel: any

Steps to reproduce

1. Define a container with a hook that has no timeout field set
2. Make the hook process hang indefinitely (e.g. sleep infinity)
3. Observe urunc never completes Exec() with no error logged

Note

This issue was identified during a code review of the hook execution
path. The code path has been manually verified by the contributor.

[cmainas]

Hello @Chennamma-Hotkar , please do not open PRs for unverified issues.

Setting a timeout is optional and up to the runtime. We can add it, but it should be big enough and therefore I doubt how much it will help