SegFault when applying redactions overlapping a transparent image

[JorjMcKie]

Please provide all mandatory information!

Describe the bug (mandatory)

If a redaction rectangle overlaps an image with a mask (= image with transparency) and page.apply_redactions(images=fitz.PDF_REDACT_IMAGE_PIXELS) is used (the default), the interpreter crashes with segmentation fault. Verified under Linux and Windows.

To Reproduce (mandatory)

Execute with the attached reproducer PDF:

import fitz
doc=fitz.open("input.pdf")
page=doc[0]
page.apply_redactions()

input.pdf

Your configuration (mandatory)

In [2]: print(fitz.__doc__)

PyMuPDF 1.20.0: Python bindings for the MuPDF 1.20.1 library.
Version date: 2022-06-27 00:00:01.
Built for Python 3.9 on win32 (64-bit).

In [2]: print(fitz.__doc__)

PyMuPDF 1.20.0: Python bindings for the MuPDF 1.20.1 library.
Version date: 2022-06-27 00:00:01.
Built for Python 3.8 on linux (64-bit).

Additional context (optional)

This is also the case for other Python versions - tested up to Python 3.10.
It did work (although with bugs - see comment at the bottom of this) in v 1.19.x.
When recompiling under Windows (Linux yet to be confirmed), things will work again as before.
The error occurs in

which invokes this C-code:

---

Please note that for transparent images, the MuPDF code will produce a PNG image without transparency.
This is a known problem and does not otherwise interfere with this bug.
Using one of the other options for handling images with redactions continue to work fine.

[JorjMcKie]

The error is caused inside MuPDF and will be fixed there.

[JorjMcKie]

As a side note:

Once this MuPDF version (and its resp. PyMuPDF version) is out, the older issue of supporting transparent images with redactions will also be solved.

[julian-smith-artifex-com]

Fixed in recent release of PyMuPDF-1.20.2.