[MESOS-3335] FlagsBase copy-ctor leads to dangling pointer.

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.2.0
• Labels: mesosphere
• Target Version/s: 1.2.0
• Sprint: Mesosphere Sprint 44, Mesosphere Sprint 45
• Story Points: 8
• Assignee: Benjamin Bannier
• Reporter: Neil Conway
• Shepherd: Michael Park
• Created: 30/Aug/15 01:45
• Updated: 26/Nov/18 09:29
• Resolved: 26/Nov/18 09:29

Description

Per 3328, ubsan detects the following problem:

[ RUN ] FaultToleranceTest.ReregisterCompletedFrameworks
/mesos/3rdparty/libprocess/3rdparty/stout/include/stout/flags/flags.hpp:303:25: runtime error: load of value 33, which is not a valid value for type 'bool'

I believe what is going on here is the following:

• The test calls StartMaster(), which does MesosTest::CreateMasterFlags()
• MesosTest::CreateMasterFlags() allocates a new master::Flags on the stack, which is subsequently copy-constructed back to StartMaster()
• The FlagsBase constructor is:

  FlagsBase() { add(&help, "help", "...", false); }

  where "help" is a member variable – i.e., it is allocated on the stack in this case.

• FlagsBase()::add captures &help, e.g.:

  flag.stringify = [t1](const FlagsBase&) -> Option<std::string> {
      return stringify(*t1);
    };}}
  

• The implicit copy constructor for FlagsBase is just going to copy the lambda above, i.e., the result of the copy constructor will have a lambda that points into MesosTest::CreateMasterFlags()'s stack frame, which is bad news.

Not sure the right fix – comments welcome. You could define a copy-ctor for FlagsBase that does something gross (basically remove the old help flag and define a new one that points into the target of the copy), but that seems, well, gross.

Probably not a pressing-problem to fix – AFAICS worst symptom is that we end up reading one byte from some random stack location when serving state.json, for example.

Issue Links

• relates to: MESOS-5745 AuthenticationTest.UnauthenticatedSlave fails with clang++3.8
• relates to: MESOS-5841 Clean up `FlagsBase::add`