[webkit-changes] [WebKit/WebKit] 682fa4: Check pixel buffer before dereferencing

[JC Alvarado]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 682fa4507d4d42682ffc76a8a9703c30dbd91e1d
      https://github.com/WebKit/WebKit/commit/682fa4507d4d42682ffc76a8a9703c30dbd91e1d
  Author: JC Alvarado <joncarlo at apple.com>
  Date:   2023-03-10 (Fri, 10 Mar 2023)

  Changed paths:
    A LayoutTests/fast/html/canvas-integer-overflow-expected.txt
    A LayoutTests/fast/html/canvas-integer-overflow.html
    M Source/WebCore/html/canvas/CanvasRenderingContext2DBase.cpp

  Log Message:
  -----------
  Check pixel buffer before dereferencing
https://bugs.webkit.org/show_bug.cgi?id=253686
rdar://106492794

Reviewed by Aditya Keerthi.

When calculating the area of a rect, there can be an integer overflow
that results in getPixelBuffer returning a nullptr. In this case, we
should return early from postProcessPixelBuffer.

* LayoutTests/fast/html/canvas-integer-overflow-expected.txt: Added.
* LayoutTests/fast/html/canvas-integer-overflow.html: Added.
* Source/WebCore/html/canvas/CanvasRenderingContext2DBase.cpp:
(WebCore::CanvasRenderingContext2DBase::postProcessPixelBuffer const):

Canonical link: https://commits.webkit.org/261532@main