Windows Explorer Crash on Certain PGM or PPM Image Files

Hi,

Attached are two image files that reliably crash "explorer.exe" when viewing a directory containing them:

https://geometrian.com/tmp/images_that_crash_explorer.zip

I can trace the crash to the shell extension that provides thumbnails, specifically Microsoft DirectX Shell Extensions version 9.29 in "<drive>:\Program Files (x86)\Microsoft DirectX SDK (June 2010)\Utilities\bin\x64\TxView.dll" (last built 2022-10-03 07:03:08). Disabling all aspects ("Context Menu", "InfoTip Handler", and probably most importantly "Thumbnail") of this extension using e.g. ShellExView allows Windows Explorer to view directories containing these files without crashing (though obviously without thumbnail previews).

The images in question are a PPM file and a PGM file generated from a broken renderer. The problem is likely that the PGM file erroneously has a PPM header, and so the expected data size is 3⨯ larger than the data actually contained in the file. Probably "TxView.dll" has a bug that does not detect this, and executes a buffer overrun, crashing. Any file whatsoever, valid or invalid, must not crash the module!

It's also somewhat surprising to me that the module crash brings down the whole process. It would be nice if it were sandboxed to be more robust.

OS is Windows 10 Pro (build 19045.3803), up to date.

(BTW, I'm not sure where to report issues like this. The in-OS support sent me to normal customer support, which was not remotely prepared for anything this technical. They eventually sent me to Windows developer support, which isn't really applicable because it's not my code that's faulting. When I tried to click through one of the categories anyway, it hit me with a login wall, then the website crashed. Logging in on a different browser, it wanted me to make a business support account. It shouldn't be this hard to report system bugs! Don't you want to know about them?)