From: Matt Caswell Date: Fri, 30 Jun 2017 09:45:11 +0000 (+0100) Subject: Fix TLSv1.3 exporter X-Git-Tag: OpenSSL_1_1_1-pre1~1132 X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff_plain;h=4d89bf448490e7c77743f53bfbefbaddee9b275e Fix TLSv1.3 exporter We need to use the hashsize in generating the exportsecret not 0! Otherwise we end up with random garbage for the secret. It was pure chance that this passed the tests previously. It so happens that, because we call SSL_export_keying_material() repeatedly for different scenarios in the test, we end up in the tls13_export_keying_material() at exactly the same position in the stack each time and therefore end up using the same random garbage secret each time! Reviewed-by: Tim Hudson (Merged from https://github.com/openssl/openssl/pull/3810) --- diff --git a/ssl/tls13_enc.c b/ssl/tls13_enc.c index 55e68c60db..92b1f198ab 100644 --- a/ssl/tls13_enc.c +++ b/ssl/tls13_enc.c @@ -622,7 +622,7 @@ int tls13_export_keying_material(SSL *s, unsigned char *out, size_t olen, || EVP_DigestFinal_ex(ctx, hash, &hashsize) <= 0 || !tls13_hkdf_expand(s, md, s->exporter_master_secret, (const unsigned char *)label, llen, NULL, - exportsecret, 0) + exportsecret, hashsize) || !tls13_hkdf_expand(s, md, exportsecret, exporterlabel, sizeof(exporterlabel) - 1, hash, out, olen)) goto err;