On Fri, Apr 10, 2020 at 12:02:59PM +0200, Andrea Righi wrote:

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).

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.

Prevent this problem by passing --foreground to /usr/bin/timeout, allowing to properly deliver signals to children processes.

Interesting! This seems a poor behavior on "timeout"'s part. Is it setting a signal mask? Hmpf. Thanks for tracking this down! This seems like the best solution now, so:

Acked-by: Kees Cook keescook@chromium.org

-Kees

Signed-off-by: Andrea Righi andrea.righi@canonical.com

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

diff --git a/tools/testing/selftests/kselftest/runner.sh b/tools/testing/selftests/kselftest/runner.sh index e84d901f8567..676b3a8b114d 100644 --- a/tools/testing/selftests/kselftest/runner.sh +++ b/tools/testing/selftests/kselftest/runner.sh @@ -33,7 +33,7 @@ tap_timeout() { # Make sure tests will time out if utility is available. if [ -x /usr/bin/timeout ] ; then

• /usr/bin/timeout "$kselftest_timeout" "$1"
  

• /usr/bin/timeout --foreground "$kselftest_timeout" "$1"
  

  else "$1" fi

-- 2.25.1