From fd3e4abb4665075ed71ae3a64a1d825f87379048 Mon Sep 17 00:00:00 2001
From: Jacob Barthelmeh <jacob@wolfssl.com>
Date: Thu, 7 Nov 2019 11:36:20 -0700
Subject: [PATCH] handle case to avoid memcpy when staticmemory IO pool gives
 same buffer

---
 src/internal.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/internal.c b/src/internal.c
index d6253d0c2..75ed97211 100644
--- a/src/internal.c
+++ b/src/internal.c
@@ -7651,6 +7651,16 @@ static WC_INLINE int GrowOutputBuffer(WOLFSSL* ssl, int size)
         tmp += align - hdrSz;
 #endif
 
+#ifdef WOLFSSL_STATIC_MEMORY
+    /* can be from IO memory pool which does not need copy if same buffer */
+    if (ssl->buffers.outputBuffer.length &&
+            tmp == ssl->buffers.outputBuffer.buffer) {
+        ssl->buffers.outputBuffer.bufferSize =
+            size + ssl->buffers.outputBuffer.length;
+        return 0;
+    }
+#endif
+
     if (ssl->buffers.outputBuffer.length)
         XMEMCPY(tmp, ssl->buffers.outputBuffer.buffer,
                ssl->buffers.outputBuffer.length);
@@ -7715,6 +7725,16 @@ int GrowInputBuffer(WOLFSSL* ssl, int size, int usedLength)
         tmp += align - hdrSz;
 #endif
 
+#ifdef WOLFSSL_STATIC_MEMORY
+    /* can be from IO memory pool which does not need copy if same buffer */
+    if (usedLength && tmp == ssl->buffers.inputBuffer.buffer) {
+        ssl->buffers.inputBuffer.bufferSize = size + usedLength;
+        ssl->buffers.inputBuffer.idx    = 0;
+        ssl->buffers.inputBuffer.length = usedLength;
+        return 0;
+    }
+#endif
+
     if (usedLength)
         XMEMCPY(tmp, ssl->buffers.inputBuffer.buffer +
                     ssl->buffers.inputBuffer.idx, usedLength);