[Bug 1397250] Re: SIGPIPE not caught in do_atfork_child()

[Jon Grimm]

Tested version libnss-ldap_264-2.2ubuntu4.14.04.2 on amd64 from trusty-
proposed.

ubuntu at tldapclient:~$ ./testhosts.pl 
Parent!
Child!
Done!
Parent wake!
Done!

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https://bugs.launchpad.net/bugs/1397250

Title:
  SIGPIPE not caught in do_atfork_child()

Status in nss_ldap:
  Fix Released
Status in libnss-ldap package in Ubuntu:
  Fix Released
Status in libnss-ldap source package in Trusty:
  Fix Committed
Status in libnss-ldap source package in Xenial:
  Won't Fix
Status in libnss-ldap source package in Yakkety:
  Won't Fix

Bug description:
  [Impact]

   * If a process using libnss-ldap calls fork() and SIGPIPE was blocked, 
     the atfork() handler in the child process failed to catch the SIGPIPE 
     as it was supposed to do, that is in the call to  do_close_no_unbind().
     So that, the uncaught SIGPIPE will be eventually delivered when the
     child unblocks signals. This usually make the child process die
     unexpectedly.

   * This is only reproducible when ldap is configured for STARTTLS.

   * Upstream fix has been long integrated.

  [Test Case]

   * See https://bugs.launchpad.net/ubuntu/trusty/+source/libnss-
  ldap/+bug/1397250/comments/19

  
  [Regression Potential] 

   * Fix has been upstream since 2010, and limited to path of child
     forking, and SIGPIPE is blocked. No consequent bugs or regressions
     in the upstream blamed on this change.  

  
  [Other Info]
   
   * I'm currently limiting my SRU to trusty, as I'm unable to 
     recreate the bug on xenial.  Even so, I have tested the fixed 
     code on xenial to ensure there was no regression with the testcase.

   * Will look at fixing xenial too, IFF someone comes forward able to
     reproduce the bug/validate the fix.

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