compiz crashed with SIGSEGV in g_bit_lock()

[Walter Ribeiro]

Error occurred while trying to unlock from launcher disk volume icon using context menu.
The error can be reproduced.

ProblemType: Crash
DistroRelease: Ubuntu 15.10
Package: unity 7.3.2+15.10.20150910.1-0ubuntu1
ProcVersionSignature: Ubuntu 4.2.0-7.7-generic 4.2.0
Uname: Linux 4.2.0-7-generic x86_64
ApportVersion: 2.18.1-0ubuntu1
Architecture: amd64
CrashCounter: 1
CurrentDesktop: Unity
Date: Sun Sep 13 01:10:59 2015
ExecutablePath: /usr/bin/compiz
InstallationDate: Installed on 2015-09-13 (0 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Alpha amd64 (20150911)
ProcCmdline: compiz
SegvAnalysis:
 Segfault happened at: 0x7f33bc884338 <g_bit_lock+72>: lock bts %r12d,(%rbx)
 PC (0x7f33bc884338) ok
 source "%r12d" ok
 destination "(%rbx)" (0x00000020) not located in a known VMA region (needed writable region)!
SegvReason: writing NULL VMA
Signal: 11
SourcePackage: unity
StacktraceTop:
 g_bit_lock () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
 ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
 g_variant_serialiser_needed_size () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
 ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
 ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
Title: compiz crashed with SIGSEGV in g_bit_lock()
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo

[Apport retracing service (apport)]

StacktraceTop:
 g_bit_lock (address=address@entry=0x20, lock_bit=lock_bit@entry=0) at /build/glib2.0-hcw3A1/glib2.0-2.45.7/./glib/gbitlock.c:214
 g_variant_lock (value=0x0) at /build/glib2.0-hcw3A1/glib2.0-2.45.7/./glib/gvariant-core.c:221
 g_variant_fill_gvs (serialised=0x7ffe529046f0, data=0x0) at /build/glib2.0-hcw3A1/glib2.0-2.45.7/./glib/gvariant-core.c:399
 gvs_variable_sized_array_needed_size (n_children=2, children=0x1b916e0, gvs_filler=0x7f33bc8e9700 <g_variant_fill_gvs>, type_info=<optimized out>) at /build/glib2.0-hcw3A1/glib2.0-2.45.7/./glib/gvariant-serialiser.c:709
 g_variant_serialiser_needed_size (type_info=<optimized out>, gvs_filler=gvs_filler@entry=0x7f33bc8e9700 <g_variant_fill_gvs>, children=0x1b916e0, n_children=2) at /build/glib2.0-hcw3A1/glib2.0-2.45.7/./glib/gvariant-serialiser.c:1434

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Lars Karlitski (larsu)]

This is not a bug in glib. UploadBlacklist() loops through a list of strings with

  for (auto item : blacklist_)
    // do something with item.c_str()

which makes a copy of each string in every iteration. This means that item.c_str() is not valid anymore after the loop finishes. g_settings_set_strv() then rightly complains about invalid utf8 from whatever is lying around at those memory addresses then.

The attached branch fixes this by using a const reference in the loop.

[Launchpad Janitor (janitor)]

This bug was fixed in the package unity - 7.3.2+15.10.20150921-0ubuntu1

---------------
unity (7.3.2+15.10.20150921-0ubuntu1) wily; urgency=medium

  [ Andrea Azzarone ]
  * Avoid to open adjacent menu when moving from an indicator icon to
    its dropdown menu. (LP: #552920)
  * Make sure to restore the state before the call to
    glDisable(GL_SCISSOR_TEST). (LP: #1485727)

  [ Iain Lane ]
  * launcher: Always make sure we check the right file when seeing if
    .desktop files have been deleted. Fixes disappearing launcher icons
    when applications are upgraded when we are using glib > 2.44. (LP:
    #1498106)

  [ Lars Uebernickel ]
  * DevicesSettingsImp: dont't feed garbage to gsettings (LP: #1495173)

  [ Luke Yelavich ]
  * Make a copy of a quicklist menu item plain text label
  * Make a copy of a quicklist menu item plain text label

  [ Marco Trevisan (Treviño) ]
  * MenuManager: add a new setting to control the show-now delay (LP:
    #1497915)

 -- Marco Trevisan (Treviño) <[e-mail]> Mon, 21 Sep 2015 17:44:10 +0000