[OpenSIPS-Devel] [OpenSIPS/opensips] ac549a: async: fix fd leaking and invalid memory overwrite

[Razvan Crainea]

  Branch: refs/heads/master
  Home:   https://github.com/OpenSIPS/opensips
  Commit: ac549a0d5f3a084cd7034bf45b603f95c64025af
      https://github.com/OpenSIPS/opensips/commit/ac549a0d5f3a084cd7034bf45b603f95c64025af
  Author: Razvan Crainea <razvan at opensips.org>
  Date:   2018-10-03 (Wed, 03 Oct 2018)

  Changed paths:
    M async.c
    M modules/tm/async.c

  Log Message:
  -----------
  async: fix fd leaking and invalid memory overwrite

when calling `reactor_del_reader(*fd, ...)`, the `*fd` will become -1.
The reason is because `fd` points to a `io_wait_h->fd_no`, that will get
changed to `-1` at the end of the function. Hence the actual `*fd` value
will be lost, and `close(*fd)` is a no-op, resulting in original fd
leaking. Moreover, when assigning `*fd` a new value, we will be
overwriting the `io_wait_h->fd_no` in the reactor, resulting in
undefined behavior.
This commit stores the actual value of `*fd` in a local variable and
uses it throught the function, making sure the `io_wait_h->fd_no` is not
overwritten and the `close()` function is called on the proper fd.

Many thangs to Eric Tamme (lirakis) on IRC for reporting this.



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