From e7b0fefd7ae03468a91c5765b120820d7a7f3f47 Mon Sep 17 00:00:00 2001
From: Jacob Barthelmeh <jacob@wolfssl.com>
Date: Thu, 1 Mar 2018 09:28:08 -0700
Subject: [PATCH] add sanity check on read index

---
 wolfcrypt/src/asn.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/wolfcrypt/src/asn.c b/wolfcrypt/src/asn.c
index f9c8589d1..d71db8707 100755
--- a/wolfcrypt/src/asn.c
+++ b/wolfcrypt/src/asn.c
@@ -3482,6 +3482,9 @@ int wc_RsaPublicKeyDecode(const byte* input, word32* inOutIdx, RsaKey* key,
             return ASN_PARSE_E;
 
         /* Option NULL ASN.1 tag */
+        if (*inOutIdx  >= inSz) {
+            return BUFFER_E;
+        }
         if (input[*inOutIdx] == ASN_TAG_NULL) {
             ret = GetASNNull(input, inOutIdx, inSz);
             if (ret != 0)