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@xxxxxxxxxxxx>
-Kees
>
> Signed-off-by: Andrea Righi <andrea.righi@xxxxxxxxxxxxx>
> ---
> 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
>
--
Kees Cook
