File openssl-CVE-2016-6302.patch of Package openssl.6981

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File openssl-CVE-2016-6302.patch of Package openssl.6981

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-1.0.1i/ssl/t1_lib.c
===================================================================
--- openssl-1.0.1i.orig/ssl/t1_lib.c	2016-09-22 14:54:08.914883013 +0200
+++ openssl-1.0.1i/ssl/t1_lib.c	2016-09-22 14:55:13.939900918 +0200
@@ -2332,9 +2332,7 @@ 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)
-		return 2;
+
 	/* Initialize session ticket encryption and HMAC contexts */
 	HMAC_CTX_init(&hctx);
 	EVP_CIPHER_CTX_init(&ctx);
@@ -2369,6 +2367,14 @@ static int tls_decrypt_ticket(SSL *s, co
 		EVP_CIPHER_CTX_cleanup(&ctx);
 		return -1;
 		}
+
+    /* 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);
+        return 2;
+    }
+
 	eticklen -= mlen;
 	/* Check HMAC of encrypted ticket */
 	HMAC_Update(&hctx, etick, eticklen);

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File openssl-CVE-2016-6302.patch of Package openssl.6981

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