From d5d983e16830b1a131b08c8f7746398a256a7e58 Mon Sep 17 00:00:00 2001
From: Gilles Peskine <Gilles.Peskine@arm.com>
Date: Fri, 15 Jun 2018 14:05:10 +0200
Subject: [PATCH] ssl_server2: handle mbedtls_x509_dn_gets failure

If mbedtls_x509_dn_gets fails, the server could end up calling printf
on an uninitialized buffer. Check if the function succeeds. Found by
Coverity.
---
 programs/ssl/ssl_server2.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/programs/ssl/ssl_server2.c b/programs/ssl/ssl_server2.c
index 81041c44d..3a413ad5e 100644
--- a/programs/ssl/ssl_server2.c
+++ b/programs/ssl/ssl_server2.c
@@ -962,8 +962,9 @@ static int ssl_async_start( mbedtls_ssl_context *ssl,
 
     {
         char dn[100];
-        mbedtls_x509_dn_gets( dn, sizeof( dn ), &cert->subject );
-        mbedtls_printf( "Async %s callback: looking for DN=%s\n", op_name, dn );
+        if( mbedtls_x509_dn_gets( dn, sizeof( dn ), &cert->subject ) > 0 )
+            mbedtls_printf( "Async %s callback: looking for DN=%s\n",
+                            op_name, dn );
     }
 
     /* Look for a private key that matches the public key in cert.