[openssl-commits] [openssl] master update

[Matt Caswell]

The branch master has been updated
       via  e97763c92c655dcf4af2860b3abd2bc4c8a267f9 (commit)
      from  652c52a602b4c88cfadb99e85ef175441b7f5d18 (commit)


- Log -----------------------------------------------------------------
commit e97763c92c655dcf4af2860b3abd2bc4c8a267f9
Author: Dr. Stephen Henson <steve at openssl.org>
Date:   Mon Aug 22 17:20:01 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: Viktor Dukhovni <viktor at openssl.org>

-----------------------------------------------------------------------

Summary of changes:
 ssl/t1_lib.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index 938f8be..b8f8fd2 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -2969,9 +2969,7 @@ static int tls_decrypt_ticket(SSL *s, const unsigned char *etick,
     HMAC_CTX *hctx = NULL;
     EVP_CIPHER_CTX *ctx;
     SSL_CTX *tctx = s->initial_ctx;
-    /* Need at least keyname + iv + some encrypted data */
-    if (eticklen < 48)
-        return 2;
+
     /* Initialize session ticket encryption and HMAC contexts */
     hctx = HMAC_CTX_new();
     if (hctx == NULL)
@@ -3018,6 +3016,12 @@ static int tls_decrypt_ticket(SSL *s, const unsigned char *etick,
     if (mlen < 0) {
         goto err;
     }
+    /* Sanity check ticket length: must exceed keyname + IV + HMAC */
+    if (eticklen <=
+        TLSEXT_KEYNAME_LENGTH + EVP_CIPHER_CTX_iv_length(ctx) + mlen) {
+        ret = 2;
+        goto err;
+    }
     eticklen -= mlen;
     /* Check HMAC of encrypted ticket */
     if (HMAC_Update(hctx, etick, eticklen) <= 0