TT#16684 Cleanup OpenSSL state properly on a threaded program

With newer OpenSSL versions it seems a threaded application needs to
cleanup properly, otherwise the now automatic atexit() cleanup handler
will segfault when the pthread variables have been deallocated already
by the pthreads library.

Change-Id: I08ac91cf63b1a74c17a0bd70b40202a5baf7771f

debian/patches/series

@@ -49,3 +49,4 @@ sipwise/tm-deep-cloning-of-the-request-for-fake-environment.patch
 sipwise/core-parser-reset_path_vector-remove-check-for-msg-m.patch
 sipwise/pv_trans_eval_uri.patch
 sipwise/rtpengine-mos-stats.patch
+sipwise/openssl-pthreads-cleanup.patch

debian/patches/sipwise/openssl-pthreads-cleanup.patch

@@ -0,0 +1,38 @@
+Description: Explicitly call OPENSSL_cleanup() on TLS module destruction
+ Kamailio is a threaded program, and it pulls OpenSSL via a dynamically
+ linked plugin loaded at run-time via dlopen().
+ .
+ Older OpenSSL releases do not perform automatic cleanup on exit, newer ones
+ do via an atexit() handler.
+ .
+ In addition the OpenSSL code leaks (on purpose) a DSO handler for itself so
+ that it can guarantee that the library is still present when the atexit()
+ handler is executed.
+ .
+ When the handler is called, a pthread variable is still present but the
+ memory it points to is not allocated anymore, which indicates something else
+ released those pthread memory pools. Most probably pthreads itself as part
+ of its deconstructors, pthread_exit() or atexit() handlers while unwinding
+ or being unloaded.
+ .
+ Explicitly calling the OpenSSL cleanup code fixes the issue for newer
+ OpenSSL releases, where this has been made visible. And the documentation
+ for OPENSSL_cleanup() mentions that explicit cleanup might be needed in
+ these conditions anyway.
+Origin: other, Sipwise
+Author: Guillem Jover <gjover@sipwise.com>
+Bug-Debian: https://bugs.debian.org/870018
+
+---
+
+--- a/modules/tls/tls_init.c
++++ b/modules/tls/tls_init.c
+@@ -778,4 +778,8 @@ void destroy_tls_h(void)
+ 	tls_destroy_cfg();
+ 	tls_destroy_locks();
+ 	tls_ct_wq_destroy();
++
++#if OPENSSL_VERSION_NUMBER >= 0x010100000L
++	OPENSSL_cleanup();
++#endif
+ }