From 38ac4415a9cc4cca307c866e5fc548b889fe2bb6 Mon Sep 17 00:00:00 2001
From: Bernd Edlinger <bernd.edlinger@hotmail.de>
Date: Mon, 22 Nov 2021 21:50:04 +0100
Subject: [PATCH] Prevent crash with engine using different openssl runtime

This problem happens usually because an application
links libcrypto and/or libssl statically which
installs an atexit handler, but later an engine using
a shared instance of libcrypto is installed.
The problem is in simple words that both instances
of libcrypto have an atexit handler installed,
but both are unable to coordinate with each other,
which causes a crash, typically a use-after-free
in the engine's destroy function.

Work around that by preventing the engine's
libcrypto to install the atexit handler.
This may result in a small memory leak, but that
memory is still reachable.

Fixes #15898

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17541)
---
 include/openssl/engine.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/openssl/engine.h b/include/openssl/engine.h
index 0780f0fb5f..756751c6d3 100644
--- a/include/openssl/engine.h
+++ b/include/openssl/engine.h
@@ -722,6 +722,7 @@ typedef int (*dynamic_bind_engine) (ENGINE *e, const char *id,
             CRYPTO_set_mem_functions(fns->mem_fns.malloc_fn, \
                                      fns->mem_fns.realloc_fn, \
                                      fns->mem_fns.free_fn); \
+            OPENSSL_init_crypto(OPENSSL_INIT_NO_ATEXIT, NULL); \
         skip_cbs: \
             if (!fn(e, id)) return 0; \
             return 1; }
-- 
2.38.1.windows.1

