From 668f6f08c62177ab5893fc26ebb67053aafdffc8 Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Thu, 12 Mar 2015 14:37:26 +0000
Subject: [PATCH] Add sanity check to PRF

The function tls1_PRF counts the number of digests in use and partitions
security evenly between them. There always needs to be at least one digest
in use, otherwise this is an internal error. Add a sanity check for this.

Reviewed-by: Richard Levitte <levitte@openssl.org>
---
 ssl/t1_enc.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/ssl/t1_enc.c b/ssl/t1_enc.c
index 1833eb7646..26f8415dcb 100644
--- a/ssl/t1_enc.c
+++ b/ssl/t1_enc.c
@@ -260,6 +260,11 @@ static int tls1_PRF(long digest_mask,
         if ((m << TLS1_PRF_DGST_SHIFT) & digest_mask)
             count++;
     }
+    if(!count) {
+        /* Should never happen */
+        SSLerr(SSL_F_TLS1_PRF, ERR_R_INTERNAL_ERROR);
+        goto err;
+    }
     len = slen / count;
     if (count == 1)
         slen = 0;
-- 
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