Fd resue race causes runc init can't start due to a go stdlib bug

[kolyshkin]

Description

From https://cirrus-ci.com/task/6471857094787072:

=== RUN TestInitJoinPID
exec_test.go:1471: unexpected error: unable to start container process: unable to start init: fork/exec /proc/self/fd/7: permission denied
--- FAIL: TestInitJoinPID (0.29s)

I've only seen it happen once. Filing for visibility.

EDIT:
It's not a flaky test, but a really bug in practice.

[kolyshkin]

CentOS 7 is gone (see #4333), so this one can be closed I guess.

[kolyshkin]

I saw this once on Ubuntu 24.04 now:

https://github.com/opencontainers/runc/actions/runs/10823144914/job/30028174423?pr=4358

...
=== RUN   TestSharedPidnsInitKill
--- PASS: TestSharedPidnsInitKill (0.18s)
=== RUN   TestInitJoinPID
    exec_test.go:1444: unexpected error: unable to start container process: unable to start init: fork/exec /proc/self/fd/7: permission denied
--- FAIL: TestInitJoinPID (0.14s)
=== RUN   TestInitJoinNetworkAndUser
--- PASS: TestInitJoinNetworkAndUser (0.33s)
=== RUN   TestTmpfsCopyUp
...

So it might be a genuine issue with the test case.

[kolyshkin]

One more, in test (ubuntu-20.04, 1.23.x, criu-dev) but with a different test. From logs

=== RUN   TestSeccompPermitWriteMultipleConditions
    seccomp_test.go:251: |: unable to start container process: unable to start init: fork/exec /proc/self/fd/7: permission denied
--- FAIL: TestSeccompPermitWriteMultipleConditions (0.13s)

[kolyshkin]

Another failure in test (ubuntu-20.04, 1.23.x, -race). From the logs:

=== RUN   TestSeccompDenyWriteConditional
    seccomp_test.go:205: unexpected error: unable to start container process: unable to start init: fork/exec /proc/self/fd/7: permission denied
--- FAIL: TestSeccompDenyWriteConditional (0.14s)

[kolyshkin]

From https://github.com/opencontainers/runc/actions/runs/11300641540/job/31433805394?pr=4441 (cross-i386):

=== RUN   TestRootfsPropagationSharedMount
    exec_test.go:1288: unexpected error: unable to start container process: unable to start init: fork/exec /proc/self/fd/7: permission denied
--- FAIL: TestRootfsPropagationSharedMount (0.13s)