User having trouble attaching images on Linux

[David N.]

A member reported having problem uploading images, here's what he's saying: 

Quote

Im transitioning to Linux Mint and retiriing my old system for internet use. Im having trouble uploading images. In the thread I started, as mentioned, dragging an image took the whole session down. Ive done a little test post in The Lounge - How to attach files to your posts thread. I did a small screenshot (8.3kb PNG) of The Lounge heading and it uploads but it comes out garbled. I am using Firefox, the sandbox Firejail, if thats helpful.

Here's the link to his comment with the garbled image: https://www.logicprohelp.com/forums/topic/121052-how-to-attach-files-to-your-post/#comment-858918

[ThunderBlue]

Hello. I am using Linux Mint and cannot reproduce the problem. Does this happen with other browsers as well? Should check for any plugins installed in firefox

[Makoto]

I saw this reported recently. If I remember correctly, it's an issue with Firefox itself. Specifically, an issue with how Firefox is scaling certain images client-side, meaning it's entirely a client-side issue and not fixable server-side.

Not sure if this has been addressed in newer releases or not, but have them make sure Firefox is updated anyways.

Edited March 28, 2023 by Makoto

[Makoto]

This was a bit difficult to track down but I think this may be the cause of your issue. Especially when you mention the user running a jailed version of Firefox, meaning they're likely very security conscious with their browser settings and may have this enabled.

https://discourse.mozilla.org/t/firefox-corrupts-any-image-i-paste-in-on-both-linux-and-windows/83459

The image you're pasting does somewhat appear like it's an entropy dump like in the above, so it's possible this is what they are experiencing. Have them take a look at this setting and try disabling it to see if that fixes the issue.

If it does, there's not really much that can be done to prevent it from happening in IPS itself outside of them keeping it disabled, or granting your site specifically permission to access that data.

Edited March 28, 2023 by Makoto

[David N.]

Great! Thanks so much for tracking this down @Makoto, really helpful. 🙂 

[Makoto]

No problem, happy I could help!

[David N.]

4 hours ago, Makoto said:

Have them take a look at this setting and try disabling it to see if that fixes the issue.

So he disabled that setting and then it worked however he then said: "Canvas fingerprinting is one of the sneakiest methods sites use these days to track visitors."

I'm not sure exactly if Invision is using Canvas fingerprinting to track visitors? I can't imagine why it would do that? 

[Makoto]

It's not. It's using the canvas to resize images client side if I remember correctly.

Canvas is not something made for fingerprinting, some people have found ways to exploit it to do such however. Completely disabling it is a nuclear option to combat that and will result in some browser functionality breaking as a result, which is what you're seeing happen here.

[David N.]

Ok thanks!