From f97ca1c1cae860a6c5fcae04dafa41e703d4518a Mon Sep 17 00:00:00 2001
From: Jacob Barthelmeh <jacob@wolfssl.com>
Date: Mon, 7 Jun 2021 19:44:05 +0700
Subject: [PATCH] adjust test case and add useful comments

---
 tests/api.c         | 1 +
 wolfcrypt/src/asn.c | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/tests/api.c b/tests/api.c
index 4838780a4..430bc1c35 100644
--- a/tests/api.c
+++ b/tests/api.c
@@ -21045,6 +21045,7 @@ static int test_wc_ecc_signVerify_hash (void)
     /* Init stack var */
     XMEMSET(sig, 0, siglen);
     XMEMSET(&key, 0, sizeof(key));
+    XMEMSET(adjustedSig, 0, ECC_BUFSIZE+1);
 
     /* Init structs. */
     ret = wc_InitRng(&rng);
diff --git a/wolfcrypt/src/asn.c b/wolfcrypt/src/asn.c
index f52bbeb8d..dad5d5c6b 100644
--- a/wolfcrypt/src/asn.c
+++ b/wolfcrypt/src/asn.c
@@ -15965,6 +15965,8 @@ int DecodeECC_DSA_Sig_Bin(const byte* sig, word32 sigLen, byte* r, word32* rLen,
         XMEMCPY(s, (byte*)sig + idx, len);
 
 #ifndef NO_STRICT_ECDSA_LEN
+    /* sanity check that the index has been advanced all the way to the end of
+     * the buffer */
     if (idx + len != sigLen) {
         ret = ASN_ECC_KEY_E;
     }
@@ -16006,6 +16008,8 @@ int DecodeECC_DSA_Sig(const byte* sig, word32 sigLen, mp_int* r, mp_int* s)
     }
 
 #ifndef NO_STRICT_ECDSA_LEN
+    /* sanity check that the index has been advanced all the way to the end of
+     * the buffer */
     if (idx != sigLen) {
         mp_clear(r);
         mp_clear(s);