- Johan van Selst found and fixed a OpenSSL session ref count leak:

ossl_connect_step3() increments an SSL session handle reference counter on
  each call. When sessions are re-used this reference counter may be
  incremented many times, but it will be decremented only once when done (by
  Curl_ossl_session_free()); and the internal OpenSSL data will not be freed
  if this reference count remains positive. When a session is re-used the
  reference counter should be corrected by explicitly calling
  SSL_SESSION_free() after each consecutive SSL_get1_session() to avoid
  introducing a memory leak.

  (http://curl.haxx.se/bug/view.cgi?id=2926284)

CHANGES

@@ -6,6 +6,20 @@
 
                                   Changelog
 
+Daniel Stenberg (9 Jan 2010)
+- Johan van Selst found and fixed a OpenSSL session ref count leak:
+
+  ossl_connect_step3() increments an SSL session handle reference counter on
+  each call. When sessions are re-used this reference counter may be
+  incremented many times, but it will be decremented only once when done (by
+  Curl_ossl_session_free()); and the internal OpenSSL data will not be freed
+  if this reference count remains positive. When a session is re-used the
+  reference counter should be corrected by explicitly calling
+  SSL_SESSION_free() after each consecutive SSL_get1_session() to avoid
+  introducing a memory leak.
+
+  (http://curl.haxx.se/bug/view.cgi?id=2926284)
+
 Daniel Stenberg (7 Jan 2010)
 - Make sure the progress callback is called repeatedly even during very slow
   name resolves when c-ares is used for resolving.

RELEASE-NOTES

@@ -42,6 +42,7 @@ This release includes the following bugfixes:
  o header include fix for FreeBSD versions before v8
  o fragment part of URLs are no longer sent to the server
  o progress callback called repeatedly with c-ares for resolving
+ o OpenSSL session id ref count leak
 
 This release includes the following known bugs:
 
@@ -54,6 +55,7 @@ advice from friends like these:
  Marco Maggi, Camille Moncelier, Claes Jakobsson, Kevin Baughman,
  Marc Kleine-Budde, Jad Chamcham, Bjorn Augustsson, David Byron,
  Markus Koetter, Chad Monroe, Martin Storsjo, Siegfried Gyuricsko,
- Jon Nelson, Julien Chaffraix, Renato Botelho, Peter Pentchev, Ingmar Runge
+ Jon Nelson, Julien Chaffraix, Renato Botelho, Peter Pentchev, Ingmar Runge,
+ Johan van Selst
 
         Thanks! (and sorry if I forgot to mention someone)

lib/ssluse.c

@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2009, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2010, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -2315,7 +2315,15 @@ ossl_connect_step3(struct connectdata *conn,
       return retcode;
     }
   }
-
+#ifdef HAVE_SSL_GET1_SESSION
+  else {
+    /* Session was incache, so refcount already incremented earlier.
+     * Avoid further increments with each SSL_get1_session() call.
+     * This does not free the session as refcount remains > 0
+     */
+    SSL_SESSION_free(our_ssl_sessionid);
+  }
+#endif
 
   /*
    * We check certificates to authenticate the server; otherwise we risk