[tor-bugs] #20100 [- Select a component]: persistent libxul.so bug crashing TBB Linux/64 (but probably a bug in locally linked shared object)

Tor Bug Tracker & Wiki blackhole at torproject.org
Wed Sep 7 14:40:44 UTC 2016


#20100: persistent libxul.so bug crashing TBB Linux/64 (but probably a bug in
locally linked shared object)
-------------------------------------+-------------------------------------
     Reporter:  sjamaan              |      Owner:
         Type:  defect               |     Status:  new
     Priority:  Medium               |  Milestone:
    Component:  - Select a           |    Version:
  component                          |   Keywords:  libxul.so stack segment
     Severity:  Normal               |  trap
Actual Points:                       |  Parent ID:
       Points:                       |   Reviewer:
      Sponsor:                       |
-------------------------------------+-------------------------------------
 I have a TBB (Linux x86/64) that crashes every now and then (not
 reproducible as it seems quite random yet it's happening over multiple TBB
 versions): tor-browser-linux64-6.0.4_en-US.tar.xz and about 10 earlier
 versions. Both Ubuntu and Debian latest stables.

 Linux kernel log reveals the issue in libxul.so, always at the same mmap
 pointer [segment+4a4a000] Same segment in previous TBBs. The mmap range
 for libxul.so always is 04a4a000 - 04f25000.


 Kernel message:

 firefox[1202] trap stack segment ip:7f6032255894 sp:7ffc6cc8aae0 error:0
 in libxul.so[7f60305a9000+4a4a000]


 Now, libxul.so links to 69 locally installed shared libs. In future for
 tor security, I believe this is interesting to look at because they don't
 come with TBB. ldd libxul.so and see for yourself :)

 I don't see a reason in sharing my libs outside TBB because at the moment
 I can't narrow it down more specifically (problem of reproduction). Any
 tips on how to do this are welcome (strace, ptrace have not wielded any
 clues and with gdb I don't know where to start as it appears random). So
 different debugging tips are welcome ;)


 My question is simple: I want to figure out of there is a problem with my
 Linux install... So did more people with the tor-browser-linux64-6.0.4_en-
 US (and earlier) encountered crashes through libxul.so (specifically with
 the 4a4000 offset which is where the current TBB x64/64 libxul loads) ?
 With 69 linked shared objects on the local system, I think it's better to
 raise the general question on libxul crashes before diving into the
 depths.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/20100>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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