4 ms·

I had this problem a while back where I would screen share on zoom and seemingly leftover memory from videos I’d watched in the browser showed up in certain cir

I had this problem a while back where I would screen share on zoom and seemingly leftover memory from videos I’d watched in the browser showed up in certain circumstances to people viewing my screen. Utterly horrific. I believe wayland does in fact fix this issue. Does anybody have more context on what’s going on?

suby 4y ago
I've never had that happen, but that does sound pretty terrible. It might be worth installing a second browser exclusively for use with zoom as a possible temporary fix.
heavyset_go 4y ago
That's nightmare inducing.
AnotherGoodName 4y ago
A classic problem to do with hardware overlays. It's also why screenshots of videos sometimes have blacked out video in the screenshot. 'Hardware overlay' is an old video acceleration trick to write processed video straight to the output framebuffer. It bypasses the OS windowing system completely and if you as a developer get it wrong in any way you get video peeking through other apps. Video playing via a hardware overlay' has caused such issues for 30 years now. Not just on xorg or Wayland as you'll sometimes see this on windows too.
- hakfoo 4y ago
  I recall in the old days, you could get the cheap BT848/878 TV tuner cards. They just merrily piped data into the framebuffer, so if you had things configured right, it would draw a black rectangle, expecting the card to drop video on it, and the actual video would be offset 25 pixels to the left and below the.
  - LargoLasskhyfv 4y ago
    And guess what? It worked, even on NetBSD. And you could move it with the tv-stream playing without tearing. And scaling too! Still have one such thing in PCI, gathering dust in some box.
shaky-carrousel 4y ago
I have QubesOS with a VM for work and another one for personal things. The nice thing with Qubes is that I can share all the screen in the work VM and people will only see work-related windows. So it doesn't matter what I am browsing in my personal browser, nobody from the work VM can ever see it.
- kevingadd 4y ago
  I should warn you that it's quite possible for GPU memory to leak into/out of VMs, the safety model is different. So the parent's horror story could absolutely happen to you.
  - minimalist 4y ago
    I think that you are mistaken. In Qubes, none of the VMs have access to the GPU by default[0]. May you elaborate or provide some evidence to support your claim? [0]: Unless you do something "exotic" like pass the GPU through to a particular VM which is not supported and explicitly not recommended for the security reasons that you are thinking about.
  - ncmncm 4y ago
    The sharing VM has no access to any GPU. The GPU is wholly owned by the dom0 process that copies pixels to screen memory from pages mapped to VMs.
- xvilka 4y ago
  I hoped they would adopt ReactOS for their Windows containers[1]. [1] https://github.com/QubesOS/qubes-issues/issues/2809 https://github.com/QubesOS/qubes-issues/issues/2809
  - heavyset_go 4y ago
    In my experience, Wine has better support and is much more stable than ReactOS, especially when using Proton builds.
moonchild 4y ago
Nope. That's on the kernel/gpu driver-side buffer management code, not the display server. And yes, it sucks. https://arxiv.org/pdf/1804.00114.pdf https://arxiv.org/pdf/1804.00114.pdf may be of interest.
BearOso 4y ago
I'm curious--What GPU/driver were you using? I suspect Nvidia from my experience.

suby 4y ago

I've never had that happen, but that does sound pretty terrible. It might be worth installing a second browser exclusively for use with zoom as a possible temporary fix.

heavyset_go 4y ago

That's nightmare inducing.

AnotherGoodName 4y ago

A classic problem to do with hardware overlays. It's also why screenshots of videos sometimes have blacked out video in the screenshot. 'Hardware overlay' is an old video acceleration trick to write processed video straight to the output framebuffer. It bypasses the OS windowing system completely and if you as a developer get it wrong in any way you get video peeking through other apps. Video playing via a hardware overlay' has caused such issues for 30 years now. Not just on xorg or Wayland as you'll sometimes see this on windows too.

hakfoo 4y ago
I recall in the old days, you could get the cheap BT848/878 TV tuner cards. They just merrily piped data into the framebuffer, so if you had things configured right, it would draw a black rectangle, expecting the card to drop video on it, and the actual video would be offset 25 pixels to the left and below the.
- LargoLasskhyfv 4y ago
  And guess what? It worked, even on NetBSD. And you could move it with the tv-stream playing without tearing. And scaling too! Still have one such thing in PCI, gathering dust in some box.

shaky-carrousel 4y ago

I have QubesOS with a VM for work and another one for personal things. The nice thing with Qubes is that I can share all the screen in the work VM and people will only see work-related windows. So it doesn't matter what I am browsing in my personal browser, nobody from the work VM can ever see it.

kevingadd 4y ago
I should warn you that it's quite possible for GPU memory to leak into/out of VMs, the safety model is different. So the parent's horror story could absolutely happen to you.
- minimalist 4y ago
  I think that you are mistaken. In Qubes, none of the VMs have access to the GPU by default[0]. May you elaborate or provide some evidence to support your claim? [0]: Unless you do something "exotic" like pass the GPU through to a particular VM which is not supported and explicitly not recommended for the security reasons that you are thinking about.
- ncmncm 4y ago
  The sharing VM has no access to any GPU. The GPU is wholly owned by the dom0 process that copies pixels to screen memory from pages mapped to VMs.
xvilka 4y ago
I hoped they would adopt ReactOS for their Windows containers[1]. [1] https://github.com/QubesOS/qubes-issues/issues/2809 https://github.com/QubesOS/qubes-issues/issues/2809
- heavyset_go 4y ago
  In my experience, Wine has better support and is much more stable than ReactOS, especially when using Proton builds.

moonchild 4y ago

Nope. That's on the kernel/gpu driver-side buffer management code, not the display server. And yes, it sucks. https://arxiv.org/pdf/1804.00114.pdf https://arxiv.org/pdf/1804.00114.pdf may be of interest.

BearOso 4y ago

I'm curious--What GPU/driver were you using? I suspect Nvidia from my experience.