Re: [PATCH] Manually cleanup OpenSSL from dovecot_openssl_common_global_unref()

Am 13.11.2016 um 19:04 schrieb Apollon Oikonomopoulos:

OpenSSL 1.1 features a cleanup function that is automatically run on shutdown using atexit(3). This function frees all OpenSSL-allocated resources.

In dovecot, OpenSSL is loaded indirectly using dlopen(3) against the relevant dovecot crypto module and is finally unloaded using dlclose(3). Until OpenSSL 1.0.1c this worked fine, however OpenSSL 1.0.1c makes sure[1] that the library stays loaded after the initial dlclose() so that the atexit(3) handlers can run on shutdown. This, together with the fact that dovecot uses custom allocation functions for OpenSSL and has already partially free()'d some of OpenSSL's resources in module_free(), leads to a segfault at process shutdown[2].

We fix this by explicitly calling OPENSSL_cleanup() during module unload. This is safe to do, as long as we will never want to subsequently re-initialize OpenSSL.

[1] https://github.com/openssl/openssl/commit/4af9f7fe79ff82b90c16969b7e58714350... [2] https://buildd.debian.org/status/fetch.php?pkg=dovecot&arch=amd64&ver=1:2.2.26.0-2&stamp=1478873022

Signed-off-by: Apollon Oikonomopoulos --- src/lib-ssl-iostream/dovecot-openssl-common.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/src/lib-ssl-iostream/dovecot-openssl-common.c b/src/lib-ssl-iostream/dovecot-openssl-common.c index 51ea3ad..2bf6307 100644 --- a/src/lib-ssl-iostream/dovecot-openssl-common.c +++ b/src/lib-ssl-iostream/dovecot-openssl-common.c @@ -101,6 +101,9 @@ bool dovecot_openssl_common_global_unref(void) ERR_remove_thread_state(NULL); #endif ERR_free_strings(); +#if OPENSSL_VERSION_NUMBER >= 0x10100000L + OPENSSL_cleanup(); +#endif return FALSE; }

I could at least confirm the observation (segfault on build) and the fix solve it as promised. Andreas