[tor-bugs] #22269 [Applications/Tor Browser Sandbox]: TBB Sandbox crashed after finishing bootstrap

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#22269: TBB Sandbox crashed after finishing bootstrap
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 Reporter:  leakedwiki                        |          Owner:  yawning
     Type:  defect                            |         Status:
                                              |  needs_information
 Priority:  Medium                            |      Milestone:
Component:  Applications/Tor Browser Sandbox  |        Version:
 Severity:  Normal                            |     Resolution:
 Keywords:                                    |  Actual Points:
Parent ID:                                    |         Points:
 Reviewer:                                    |        Sponsor:
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Changes (by yawning):

 * status:  reopened => needs_information


Comment:

 So yeah.  Installed ewwbuntu in a VM, and it crashes on startup
 intermittently.  Adding debugging instrumentation makes it crash less
 (race conditions are dumb).  It's not calling the xcb extension query
 routines at all from what I can tell, and it is calling my versions of the
 xlib ones.  So I have no idea why firefox (or one of it's dependencies)
 thinks it's ok to use `MIT-SHM`, when the X server doesn't appear to
 support it.

 I can't tell if anything I've tried to get it to not crash actually fixes
 the problem because behavior is intermitent.  If someone that's not me[0]
 gets a usable stack trace from when it aborts, then forward progress can
 happen here, otherwise I think this will languish in the bug tracker
 forever.

  * Forcing `layers.offmainthreadcomposition.enabled` to `false` may help.
  * Rejecting more extensions (DRI, GLX, SGI-GLX) may help.

 [0]: One upon a time I had a branch of the sandbox code that let me run
 gdb/get stack traces, but that's long since rotted, and it was a huge
 mess, that I'm not willing to clean up.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/22269#comment:7>
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