syz-ci: job: reproducer consistency is invalid errors

[a-nogikh]

We're seeing job: reproducer consistency is invalid errors once in a while.

syzkaller/syz-ci/jobs.go

Lines 416 to 417 in ff949d2

	{"reproducer consistency", (len(req.ReproOpts) != 0 && len(req.ReproSyz) != 0) ||
	(len(req.ReproOpts) == 0 && len(req.ReproSyz) == 0)},

Last time it happened on this bug: https://syzkaller.appspot.com/bug?extid=27209997e4015fb4702e

There are indeed a number of crash reports with C reports, but empty syz reports. I don't immediately understand how it could have happened.

[dvyukov]

I guess we removed all syscalls during minimization, and it still crashed :)

void execute_one(void)
{
  if (write(1, "executing program\n", sizeof("executing program\n") - 1)) {
  }
}

[a-nogikh]

Hmm, then this logic apparently does not work:

syzkaller/pkg/repro/repro.go

Lines 483 to 488 in 6f1b0fa

	res.Prog, _ = prog.Minimize(res.Prog, -1, mode, func(p1 *prog.Prog, callIndex int) bool {
	if len(p1.Calls) == 0 {
	// We do want to keep at least one call, otherwise tools/syz-execprog
	// will immediately exit.
	return false
	}

In any case, we now already have such crashes in our database. We either delete them and patch the code never to report them or we get rid of the reproducer consistency check completely.

[dvyukov]

We have another prog.Minimize call there.