From f9bdb3515d20fa9d11452fb68c761388b01e1251 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marc=20Andr=C3=A9=20Tanner?= <mat@brain-dump.org>
Date: Sat, 7 Jan 2017 13:18:05 +0100
Subject: [PATCH] buffer: make sure mem{cpy,move} are called with valid
 arguments

---
 buffer.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/buffer.c b/buffer.c
index 94c074e03..3bc89d244 100644
--- a/buffer.c
+++ b/buffer.c
@@ -70,9 +70,13 @@ bool buffer_remove(Buffer *buf, size_t pos, size_t len) {
 bool buffer_insert(Buffer *buf, size_t pos, const void *data, size_t len) {
 	if (pos > buf->len)
 		return false;
+	if (len == 0)
+		return true;
 	if (!buffer_grow(buf, buf->len + len))
 		return false;
-	memmove(buf->data + pos + len, buf->data + pos, buf->len - pos);
+	size_t move = buf->len - pos;
+	if (move > 0)
+		memmove(buf->data + pos + len, buf->data + pos, move);
 	memcpy(buf->data + pos, data, len);
 	buf->len += len;
 	return true;