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diff -up openssl-1.0.2a/doc/ssl/SSL_COMP_add_compression_method.pod.env-zlib openssl-1.0.2a/doc/ssl/SSL_COMP_add_compression_method.pod
--- openssl-1.0.2a/doc/ssl/SSL_COMP_add_compression_method.pod.env-zlib 2015-04-09 18:17:20.509637597 +0200
+++ openssl-1.0.2a/doc/ssl/SSL_COMP_add_compression_method.pod 2015-04-09 18:17:14.767504953 +0200
@@ -47,6 +47,13 @@ Once the identities of the compression m
been standardized, the compression API will most likely be changed. Using
it in the current state is not recommended.
+It is also not recommended to use compression if data transfered contain
+untrusted parts that can be manipulated by an attacker as he could then
+get information about the encrypted data. See the CRIME attack. For
+that reason the default loading of the zlib compression method is
+disabled and enabled only if the environment variable B<OPENSSL_DEFAULT_ZLIB>
+is present during the library initialization.
+
=head1 RETURN VALUES
SSL_COMP_add_compression_method() may return the following values:
diff -up openssl-1.0.2a/ssl/ssl_ciph.c.env-zlib openssl-1.0.2a/ssl/ssl_ciph.c
--- openssl-1.0.2a/ssl/ssl_ciph.c.env-zlib 2015-04-09 18:17:20.510637620 +0200
+++ openssl-1.0.2a/ssl/ssl_ciph.c 2015-04-09 18:17:20.264631937 +0200
@@ -140,6 +140,8 @@
* OTHERWISE.
*/
+/* for secure_getenv */
+#define _GNU_SOURCE
#include <stdio.h>
#include <openssl/objects.h>
#ifndef OPENSSL_NO_COMP
@@ -450,7 +452,8 @@ static void load_builtin_compressions(vo
MemCheck_off();
ssl_comp_methods = sk_SSL_COMP_new(sk_comp_cmp);
- if (ssl_comp_methods != NULL) {
+ if (ssl_comp_methods != NULL
+ && secure_getenv("OPENSSL_DEFAULT_ZLIB") != NULL) {
comp = (SSL_COMP *)OPENSSL_malloc(sizeof(SSL_COMP));
if (comp != NULL) {
comp->method = COMP_zlib();