From a06113b0c5aaa5f34b437bb1ee279dfdc9d870ea Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Sat, 18 Feb 2012 13:32:25 +0100
Subject: [PATCH] Workaround for BN_bn2mpi reading/writing out of bounds

When OpenSSL's BN_bn2mpi is passed a buffer of size 4, valgrind
reports reading/writing one byte past it. I am unable to find
evidence of this behaviour in BN_bn2mpi's source code, so it may
be a spurious warning. However, this change is harmless, as only
the bignum with value 0 results in an mpi serialization of size 4.
---
 src/bignum.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/bignum.h b/src/bignum.h
index 4143f600..a750025f 100644
--- a/src/bignum.h
+++ b/src/bignum.h
@@ -243,7 +243,7 @@ public:
     std::vector<unsigned char> getvch() const
     {
         unsigned int nSize = BN_bn2mpi(this, NULL);
-        if (nSize < 4)
+        if (nSize <= 4)
             return std::vector<unsigned char>();
         std::vector<unsigned char> vch(nSize);
         BN_bn2mpi(this, &vch[0]);