Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Sat, 28 Mar 2020 12:31:45 +0100
From:   Andrea Righi <andrea.righi@canonical.com>
To:     Kees Cook <keescook@chromium.org>
Cc:     Shuah Khan <shuah@kernel.org>, linux-kselftest@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kselftest/runner: avoid using timeout when timeout is
 disabled
Message-ID: <20200328113145.GB1371917@xps-13>
References: <20200327093620.GB1223497@xps-13>
 <202003271208.0D9A3A48CC@keescook>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <202003271208.0D9A3A48CC@keescook>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, Mar 27, 2020 at 12:28:05PM -0700, Kees Cook wrote:
> On Fri, Mar 27, 2020 at 10:36:20AM +0100, Andrea Righi wrote:
> > Avoid using /usr/bin/timeout unnecessarily if timeout is set to 0
> > (disabled) in the "settings" file for a specific test.
> 
> That seems to be a reasonable optimization, sure.
> 
> > NOTE: without this change (and adding timeout=0 in the corresponding
> > settings file - tools/testing/selftests/seccomp/settings) the
> > seccomp_bpf selftest is always failing with a timeout event during the
> > syscall_restart step.
> 
> This, however, is worrisome. I think there is something else wrong here.
> I will investigate why the output of seccomp_bpf is weird when running
> under the runner scripts. Hmmm. The output looks corrupted...

Running seccomp_bpf directly (without using runner.sh) shows this error:

 $ sudo ./tools/testing/selftests/seccomp/seccomp_bpf
 ...
 seccomp_bpf.c:2839:global.syscall_restart:Expected true (1) == WIFSTOPPED(status) (0)
 global.syscall_restart: Test terminated by assertion

Instead, running it via /usr/bin/timeout (with timeout disabled):

  $ sudo /usr/bin/timeout 0 ./tools/testing/selftests/seccomp/seccomp_bpf
  ...
  [ RUN      ] TSYNC.siblings_fail_prctl

It gets stuck here forever, basically it's during the execution of
syscall_restart().

I'll investigate more later.

Thanks,
-Andrea