From: Jean-Christophe Beaupré <jcbrinfo@users.noreply.github.com>
Date: Sun, 7 Dec 2014 05:55:36 +0000 (-0500)
Subject: ropes: Fix a buffer overflow in `RopeBuffer.add`.
X-Git-Tag: v0.7~73^2~3
X-Git-Url: http://nitlanguage.org

ropes: Fix a buffer overflow in `RopeBuffer.add`.

Signed-off-by: Jean-Christophe Beaupré <jcbrinfo@users.noreply.github.com>
---

diff --git a/lib/standard/ropes.nit b/lib/standard/ropes.nit
index 9ef2f4d..d41c021 100644
--- a/lib/standard/ropes.nit
+++ b/lib/standard/ropes.nit
@@ -337,14 +337,13 @@ class RopeBuffer
 
 	redef fun add(c) do
 		var rp = rpos
-		length += 1
-		ns[rp] = c
-		rp += 1
-		if rp == buf_size then
-			rpos = rp
+		if rp >= buf_size then
 			dump_buffer
 			rp = 0
 		end
+		ns[rp] = c
+		rp += 1
+		length += 1
 		rpos = rp
 	end
 
diff --git a/tests/sav/test_ropes_buffer_add_overflow.res b/tests/sav/test_ropes_buffer_add_overflow.res
new file mode 100644
index 0000000..e69de29
diff --git a/tests/test_ropes_buffer_add_overflow.nit b/tests/test_ropes_buffer_add_overflow.nit
new file mode 100644
index 0000000..6482b0e
--- /dev/null
+++ b/tests/test_ropes_buffer_add_overflow.nit
@@ -0,0 +1,28 @@
+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Checks that `RopeBuffer.add` does not makes the internal buffer overflow.
+#
+# Note: In order to help repoducibility, this test read an private attribute of
+# the buffer.
+module test_ropes_buffer_add_overflow
+
+import standard
+intrude import ropes
+
+var buffer = new RopeBuffer
+
+buffer.append("x" * maxlen)
+buffer.add 'y'
+assert buffer.rpos <= maxlen else print "{buffer.rpos} > {maxlen}"