780532 - Starting a video stream through getUserMedia, crashing the browser from some external issue, restarting and trying view video streams a few times eventually stops MediaStreams from working ever again

Status: RESOLVED INVALID

(Core :: WebRTC: Audio/Video, defect)

Description

[Jason Smith [:jsmith]]

Steps I did (possible my not be consistent reproduction steps):

1. Launched https://people.mozilla.com/~anarayanan/gum_test.html
2. Started the video stream
3. Went to http://mykzilla.org/app/ and selected "crash Windows"
4. After Firefox crashed, I restarted Firefox
5. I went back to https://people.mozilla.com/~anarayanan/gum_test.html
6. I launched the video and closed it a few times

Expected:

The video should launch showing my camera stream with no errors.

Actual:

The first launch of the video seemed okay, but after that, the video continued to never launch ever again. I never got an error either such as "NO_DEVICES_FOUND." I also tried on my local test case I have to ensure that this wasn't a page problem and I could also not see the video. I also tried to utilize the audio and picture functionality, but that failed as well consistently. As a result, my machine has entered a state where I can no longer make use of my camera and microphone through getUserMedia.


Note: Possible that this may not be consistently reproducible, but my machine is currently stuck in the "bad" state. If anyone can meet with me to debug what happened to my machine, feel free to stop by.

Reasoning for flagging as a security bug: If a malicious user finds a way to crash firefox (which isn't that hard to figure out), then they could easily setup a situation that crashes firefox while a media stream is running. Eventually, a user will run into this situation I've hit, in which they essentially lose the ability to utilize their camera and audio streams within the browser consistently over time (I've yet to see it work on my machine for the past hour).

Comment 1

[Jason Smith [:jsmith]]

Windows 7 Device manager currently indicates on my machine that the camera is enabled. If I try to access my sound manager right now to check the status of my microphone, the sound manager freezes and requires me to explicitly kill the process.

Comment 2

[Jason Smith [:jsmith]]

After restarting my entire machine, the video and audio stream functionality through getUserMedia started working again. I'm going to dig into this more to figure out what happened.

Comment 3

[Jason Smith [:jsmith]]

Trying my reproduction steps again in comment 0 didn't reproduce the behavior again. So why would this happen once then?

Comment 4

[Randell Jesup [:jesup] (needinfo me)]

This is very likely a bug in the DirectShow/DirectX code in Windows OR the device driver for the video and/or audio), and may well depend on hard-to-reproduce bits of state and timing (as well as DirectX/OS revision, and perhaps the device driver).

If this were not fixed (currently getUserMedia is behind a flag), AND it was semi-reliably reproducible, it might disable camera/mic until reboot only.  I think this is arguable in terms of it being a security bug at best, and likely one we can't do anything about (though that last aspect wouldn't remove it from the security category).

Comment 5

[Jason Smith [:jsmith]]

Not our bug, OS problem.