From a0f27e8273f2cdcc24778e52b279da6f55fd03b3 Mon Sep 17 00:00:00 2001
From: Vitalii Savchuk <vitaliisavchuk@cloud.upwork.com>
Date: Sat, 25 Jun 2022 12:01:53 +0300
Subject: [PATCH] fixed memory leak when layer offset lower than mask offset

---
 src/display/canvas.js | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/src/display/canvas.js b/src/display/canvas.js
index 98a6eec1fa9ec..29278d17e125c 100644
--- a/src/display/canvas.js
+++ b/src/display/canvas.js
@@ -1127,12 +1127,9 @@ function genericComposeSMask(
   const chunkSize = Math.min(height, Math.ceil(PIXELS_TO_PROCESS / width));
   for (let row = 0; row < height; row += chunkSize) {
     const chunkHeight = Math.min(chunkSize, height - row);
-    const maskData = maskCtx.getImageData(
-      layerOffsetX - maskOffsetX,
-      row + (layerOffsetY - maskOffsetY),
-      width,
-      chunkHeight
-    );
+    const maskX = Math.max(0, layerOffsetX - maskOffsetX);
+    const maskY = Math.max(0, row + (layerOffsetY - maskOffsetY));
+    const maskData = maskCtx.getImageData(maskX, maskY, width, chunkHeight);
     const layerData = layerCtx.getImageData(
       layerOffsetX,
       row + layerOffsetY,