File openssl-CVE-2016-6302.patch of Package compat-openssl098.16428
commit 1bbe48ab149893a78bf99c8eb8895c928900a16f
Author: Dr. Stephen Henson <steve@openssl.org>
Date: Tue Aug 23 18:14:54 2016 +0100
Sanity check ticket length.
If a ticket callback changes the HMAC digest to SHA512 the existing
sanity checks are not sufficient and an attacker could perform a DoS
attack with a malformed ticket. Add additional checks based on
HMAC size.
Thanks to Shi Lei for reporting this bug.
CVE-2016-6302
Reviewed-by: Rich Salz <rsalz@openssl.org>
(cherry picked from commit baaabfd8fdcec04a691695fad9a664bea43202b6)
Index: openssl-0.9.8j/ssl/t1_lib.c
===================================================================
--- openssl-0.9.8j.orig/ssl/t1_lib.c 2016-09-22 17:57:11.192433068 +0200
+++ openssl-0.9.8j/ssl/t1_lib.c 2016-09-22 18:01:03.684139923 +0200
@@ -941,9 +941,7 @@ static int tls_decrypt_ticket(SSL *s, co
HMAC_CTX hctx;
EVP_CIPHER_CTX ctx;
SSL_CTX *tctx = s->initial_ctx;
- /* Need at least keyname + iv + some encrypted data */
- if (eticklen < 48)
- goto tickerr;
+
/* Initialize session ticket encryption and HMAC contexts */
HMAC_CTX_init(&hctx);
EVP_CIPHER_CTX_init(&ctx);
@@ -972,6 +970,14 @@ static int tls_decrypt_ticket(SSL *s, co
/* Attempt to process session ticket, first conduct sanity and
* integrity checks on ticket.
*/
+
+ /* Sanity check ticket length: must exceed keyname + IV + HMAC */
+ if (eticklen <= 16 + EVP_CIPHER_CTX_iv_length(&ctx) + mlen) {
+ HMAC_CTX_cleanup(&hctx);
+ EVP_CIPHER_CTX_cleanup(&ctx);
+ goto tickerr;
+ }
+
mlen = HMAC_size(&hctx);
eticklen -= mlen;
/* Check HMAC of encrypted ticket */