id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
7611	segfault in epoll_reactor.ipp	Fredrik Jansson <fredrik.jansson.se@…>	chris_kohlhoff	"During testing of versions 1.46.1 and 1.51 on a 64-bit Ubuntu 12.04 I have found a seg fault condition in epoll_reactor.ipp.

The function is 

void epoll_reactor::deregister_descriptor(socket_type descriptor,
    epoll_reactor::per_descriptor_data& descriptor_data, bool closing)
{
  if (!descriptor_data)
    return;

  mutex::scoped_lock descriptor_lock(descriptor_data->mutex_);

  if (!descriptor_data->shutdown_)
  {

The member descriptor_data is checked for NULL before the mutex is locked, in rare conditions, when the if-statement is reached, descriptor_data is NULL.

I have solved this by adding a second check after the mutex is locked, i.e. 

  if (!descriptor_data)
    return;

  mutex::scoped_lock descriptor_lock(descriptor_data->mutex_);

  if (!descriptor_data)
    return;

  if (!descriptor_data->shutdown_)
  {

Best regards,
Fredrik Jansson"	Bugs	reopened	To Be Determined	asio	Boost 1.52.0	Problem