From e6252a94ce1278144e80e11e29d20bb6d4971567 Mon Sep 17 00:00:00 2001
From: Chris Conlon <chris@wolfssl.com>
Date: Tue, 27 Aug 2019 14:18:23 -0600
Subject: [PATCH] check attrib->value and attrib->valueSz before use

---
 wolfcrypt/src/pkcs7.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/wolfcrypt/src/pkcs7.c b/wolfcrypt/src/pkcs7.c
index ebc2f4228..c41d6b724 100644
--- a/wolfcrypt/src/pkcs7.c
+++ b/wolfcrypt/src/pkcs7.c
@@ -3447,6 +3447,9 @@ static int wc_PKCS7_VerifyContentMessageDigest(PKCS7* pkcs7,
     }
 
     /* advance past attrib->value ASN.1 header and length */
+    if (attrib->value == NULL || attrib->valueSz == 0)
+        return ASN_PARSE_E;
+
     if (attrib->value[idx++] != ASN_OCTET_STRING)
         return ASN_PARSE_E;