Clear UBsan warning -Wstringop-overflow

1 files changed, 11 insertions, 2 deletions

diff --git a/integer.cpp b/integer.cpp
index 78dd10a1..9af43bfa 100644
--- a/integer.cpp
+++ b/integer.cpp
@@ -3537,9 +3537,9 @@ class KDF2_RNG : public RandomNumberGenerator
 {

 public:

 	KDF2_RNG(const byte *seed, size_t seedSize)

-		: m_counter(0), m_counterAndSeed(seedSize + 4)

+		: m_counter(0), m_counterAndSeed(ClampSize(seedSize) + 4)

 	{

-		memcpy(m_counterAndSeed + 4, seed, seedSize);

+		memcpy(m_counterAndSeed + 4, seed, ClampSize(seedSize));

 	}

 

 	void GenerateBlock(byte *output, size_t size)

@@ -3550,6 +3550,15 @@ public:
 		P1363_KDF2<SHA1>::DeriveKey(output, size, m_counterAndSeed, m_counterAndSeed.size(), NULLPTR, 0);

 	}

 

+	// UBsan finding, -Wstringop-overflow

+	inline size_t ClampSize(size_t req) const

+	{

+		// Clamp at 16 MB

+		if (req > 16U*1024*1024)

+			return 16U*1024*1024;

+		return req;

+	}

+

 private:

 	word32 m_counter;

 	SecByteBlock m_counterAndSeed;