From 37c2aac89d93441c36ee98089b8ab33ca42b6b9a Mon Sep 17 00:00:00 2001
From: Martin Willi <martin@revosec.ch>
Date: Wed, 5 May 2010 11:26:17 +0200
Subject: [PATCH] Double-check that a blob passed to is_asn1() is not empty

---
 src/libstrongswan/asn1/asn1.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/libstrongswan/asn1/asn1.c b/src/libstrongswan/asn1/asn1.c
index 6264bdc54..6f549d42d 100644
--- a/src/libstrongswan/asn1/asn1.c
+++ b/src/libstrongswan/asn1/asn1.c
@@ -497,8 +497,14 @@ int asn1_parse_algorithmIdentifier(chunk_t blob, int level0, chunk_t *parameters
 bool is_asn1(chunk_t blob)
 {
 	u_int len;
-	u_char tag = *blob.ptr;
+	u_char tag;
 
+	if (!blob.len || !blob.ptr)
+	{
+		return FALSE;
+	}
+
+	tag = *blob.ptr;
 	if (tag != ASN1_SEQUENCE && tag != ASN1_SET && tag != ASN1_OCTET_STRING)
 	{
 		DBG2(DBG_LIB, "  file content is not binary ASN.1");