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[Bug 1199571] Re: Huge multi-threading violations in cairo

 

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------------------------------------------------------------------------
On 2014-07-29T12:20:17+00:00 Alberto Salvia Novella wrote:

I looked at the implementation of cairo-ft-font.c and it seems that
there are huge multi-threading violations in cairo. The reason is that
FreeType API documentation clearly states:

In multi-threaded applications, make sure that the same FT_Library
object or any of its children doesn't get accessed in parallel.

Cairo initializes FT_Library for its font map and there's a lock for
that, however it's only used for font map manipulations, the actual FT_
library calls are completely unprotected with that lock, although they
should be! What adds to the injury is that cairo-ft-font.c even has this
comment on one of its functions:

You must be careful when using this function in a library or in a
threaded application, because freetype's design makes it unsafe to
call freetype functions simultaneously from multiple threads, (even
if using distinct FT_Face objects)

Reply at:
https://bugs.launchpad.net/ubuntu/+source/cairo/+bug/1199571/comments/15


** Changed in: libcairo
       Status: Unknown => Confirmed

** Changed in: libcairo
   Importance: Unknown => Critical

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https://bugs.launchpad.net/bugs/1199571

Title:
  Huge multi-threading violations in cairo

Status in libcairo  -  cairo vector graphics library:
  Confirmed
Status in “cairo” package in Ubuntu:
  Triaged

Bug description:
  Fresh dist-upgrade; brought up the dash, typed "term"; single clicked
  on the terminal app and _bang_.

  ProblemType: Crash
  DistroRelease: Ubuntu 13.10
  Package: unity 7.0.2+13.10.20130705.1-0ubuntu1
  ProcVersionSignature: Ubuntu 3.10.0-2.10-generic 3.10.0
  Uname: Linux 3.10.0-2-generic x86_64
  ApportVersion: 2.10.2-0ubuntu4
  Architecture: amd64
  Date: Tue Jul  9 17:47:10 2013
  EcryptfsInUse: Yes
  ExecutablePath: /usr/bin/compiz
  InstallationDate: Installed on 2013-06-06 (33 days ago)
  InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
  MarkForUpload: True
  ProcCmdline: compiz
  ProcEnviron:
   LANGUAGE=en_US
   PATH=(custom, user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SegvAnalysis:
   Segfault happened at: 0x7ff3b4ed7a10:	mov    %rdx,0x10(%rax)
   PC (0x7ff3b4ed7a10) ok
   source "%rdx" ok
   destination "0x10(%rax)" (0x00000010) not located in a known VMA region (needed writable region)!
   Stack memory exhausted (SP below stack segment)
  SegvReason: writing NULL VMA
  Signal: 11
  SourcePackage: unity
  StacktraceTop:
   ?? () from /usr/lib/x86_64-linux-gnu/libfreetype.so.6
   ?? () from /usr/lib/x86_64-linux-gnu/libfreetype.so.6
   ?? () from /usr/lib/x86_64-linux-gnu/libfreetype.so.6
   ?? () from /usr/lib/x86_64-linux-gnu/libfreetype.so.6
   FT_Load_Glyph () from /usr/lib/x86_64-linux-gnu/libfreetype.so.6
  Title: compiz crashed with SIGSEGV in FT_Load_Glyph()
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo

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