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Bug #3248

closed

Face::Impl::ensureConnected segfault if Face is destroyed without io.poll

Added by Junxiao Shi about 9 years ago. Updated over 8 years ago.

Status:
Closed
Priority:
Normal
Assignee:
Junxiao Shi
Category:
Base
Target version:
v0.5
Start date:
10/08/2015
Due date:
% Done:

100%

Estimated time:
3.00 h

Description

Snippet to reproduce:

// g++ -o x -std=c++0x x.cpp $(pkg-config --cflags --libs libndn-cxx)
#include <ndn-cxx/face.hpp>
#include <boost/asio.hpp>

using namespace ndn;

int main()
{
  boost::asio::io_service io;

  auto face = new Face(io);
  delete face;

  io.poll(); // crash

  return 0;
}

Stack trace:

(gdb) bt
#0  0x00007ffff7884d93 in ndn::Face::Impl::ensureConnected (this=0x0, wantResume=false) at ../src/detail/face-impl.hpp:126
#1  0x00007ffff78792ba in operator() (this=0x7fffffffe290) at ../src/face.cpp:131
#2  0x00007ffff787f375 in boost::asio::asio_handler_invoke<ndn::Face::construct(std::shared_ptr<ndn::Transport>, ndn::security::KeyChain&)::<lambda()> >(struct {...}, ...) (function=...) at /usr/include/boost/asio/handler_invoke_hook.hpp:64
#3  0x00007ffff787eeb4 in boost_asio_handler_invoke_helpers::invoke<ndn::Face::construct(std::shared_ptr<ndn::Transport>, ndn::security::KeyChain&)::<lambda()>, ndn::Face::construct(std::shared_ptr<ndn::Transport>, ndn::security::KeyChain&)::<lambda()> >(struct {...} &, struct {...} &) (function=..., context=...) at /usr/include/boost/asio/detail/handler_invoke_helpers.hpp:39
#4  0x00007ffff787dad0 in boost::asio::detail::completion_handler<ndn::Face::construct(std::shared_ptr<ndn::Transport>, ndn::security::KeyChain&)::<lambda()> >::do_complete(boost::asio::detail::io_service_impl *, boost::asio::detail::operation *, const boost::system::error_code &, std::size_t) (owner=0x616780, base=0x62f7b0) at /usr/include/boost/asio/detail/completion_handler.hpp:67
#5  0x000000000040a850 in boost::asio::detail::task_io_service_operation::complete(boost::asio::detail::task_io_service&, boost::system::error_code const&, unsigned long) ()
#6  0x000000000040b58b in boost::asio::detail::task_io_service::do_poll_one(boost::asio::detail::scoped_lock<boost::asio::detail::posix_mutex>&, boost::asio::detail::op_queue<boost::asio::detail::task_io_service_operation>&, boost::system::error_code const&) ()
#7  0x000000000040b2ba in boost::asio::detail::task_io_service::poll(boost::system::error_code&) ()
#8  0x000000000040b895 in boost::asio::io_service::poll() ()
#9  0x0000000000409260 in main ()
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 #1

Updated by Alex Afanasyev almost 9 years ago

  • Target version set to v0.4
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 #2

Updated by Davide Pesavento almost 9 years ago

  • Target version changed from v0.4 to v0.5
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 #3

Updated by Junxiao Shi over 8 years ago

Root cause:
Face::construct invokes m_ioService.post([=] { m_impl->ensureConnected(false); });, where m_impl is a member field of unique_ptr<Impl> type.
When the face is deallocated, Impl is deallocated as well, and m_impl variable itself is also deallocated.
When io.poll() or io.run() is invoked the next time, m_impl variable is on freed memory, and everything after that is undefined behavior.

This problem not only occurs in a seemingly corner case "Face destroyed without io.poll()", but also can occur with all other uses of io.post and io.dispatch (in multi-threaded program).

A solution is to change m_impl to shared_ptr<Impl>, and capture a weak_ptr<Impl> in io.post and io.dispatch calls:

weak_ptr<Impl> implWeak(m_impl);
m_ioService.post([=] {
  auto impl = implWeak.lock();
  if (impl != nullptr) {
    impl->ensureConnected(false);
  }
});
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 #4

Updated by Junxiao Shi over 8 years ago

20160721 call agrees with the analysis in note-3.

Alex believes there are more bugs from the same cause.

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 #5

Updated by Junxiao Shi over 8 years ago

  • Status changed from New to In Progress
  • Assignee set to Junxiao Shi
  • Estimated time set to 3.00 h
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 #6

Updated by Junxiao Shi over 8 years ago

  • % Done changed from 0 to 40

https://gerrit.named-data.net/3025 corrects code style in face.* detail/* interest-filter.*.

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 #7

Updated by Junxiao Shi over 8 years ago

  • Status changed from In Progress to Code review
  • % Done changed from 40 to 100

https://gerrit.named-data.net/3051 has the fix.

In patchset1, I only added one test case for the scenario described in issue description.
Other io.post and io.dispatch calls may have the same issue; I fixed them but didn't add test cases.

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 #8

Updated by Junxiao Shi over 8 years ago

  • Status changed from Code review to Closed
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