[SRU][F][PATCH 0/1] kselftest: seccomp kill_after_ptrace() timeout

[Andrea Righi]

BugLink: https://bugs.launchpad.net/bugs/1872047

NOTE: if we apply this fix we can revert the following commit to
properly use timeouts in seccomp selftest:

 c6d82e6a2831 ("UBUNTU: SAUCE: selftests/seccomp -- Disable timeout for seccomp tests")

[Impact]

While running seccomp_bpf, kill_after_ptrace() gets stuck if we run it
via /usr/bin/timeout (that is the default), until the timeout expires.

This is because /usr/bin/timeout is preventing to properly deliver
signals to ptrace'd children (SIGSYS in this case).

[Test case]

This problem can be easily reproduced by running:

 $ sudo make TARGETS=seccomp kselftest
 ...

 # [ RUN ] TRACE_syscall.skip_a#
 not ok 1 selftests: seccomp: seccomp_bpf # TIMEOUT

The test is hanging at this point until the timeout expires and then it
reports the timeout error.

[Fix]

This problem can be prevented by passing --foreground to
/usr/bin/timeout, allowing to properly deliver signals to children
processes.

[Regression potential]

Not an upstream fix (patch has been sent to the lkml
https://lkml.org/lkml/2020/4/10/153), but the fix is trivial and it's
only affecting the selftests, not the kernel, so regression potential is
minimal.

----------------------------------------------------------------
Andrea Righi (1):
      UBUNTU: SAUCE: kselftest/runner: allow to properly deliver signals to tests

 tools/testing/selftests/kselftest/runner.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)