From ba77bbf840b8b70ad7f24ef516f71ed8ff340a25 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Manuel=20P=C3=A9gouri=C3=A9-Gonnard?= <mpg@elzevir.fr>
Date: Thu, 15 Aug 2013 13:38:13 +0200
Subject: [PATCH] Fix memory error in asn1_get_alg()

---
 library/asn1parse.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/library/asn1parse.c b/library/asn1parse.c
index 9d42f05916..ff566c9ce6 100644
--- a/library/asn1parse.c
+++ b/library/asn1parse.c
@@ -292,8 +292,11 @@ int asn1_get_alg( unsigned char **p,
             ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 )
         return( ret );
 
-    end = *p + len;
+    if( ( end - *p ) < 1 )
+        return( POLARSSL_ERR_ASN1_OUT_OF_DATA );
+
     alg->tag = **p;
+    end = *p + len;
 
     if( ( ret = asn1_get_tag( p, end, &alg->len, ASN1_OID ) ) != 0 )
         return( ret );