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2998ba2012
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Daniel P. Berrangé 2998ba2012 util: avoid race in releasing the GSource in event thread 
There is a race between  vir_event_thread_finalize and
virEventThreadWorker in releasing the last reference on
the GMainContext. If virEventThreadDataFree() runs after
vir_event_thread_finalize releases its reference, then
it will release the last reference on the GMainContext.
As a result g_autoptr cleanup on the GSource will access
free'd memory.

The race can be seen in non-deterministic crashes of the
virt-run-qemu program during its shutdown, but could
also likely affect the main libvirtd QEMU driver:

  Thread 2 (Thread 0x7f508ffff700 (LWP 222813)):
  #0  0x00007f509c8e26b0 in malloc_consolidate (av=av@entry=0x7f5088000020) at malloc.c:4488
  #1  0x00007f509c8e4b08 in _int_malloc (av=av@entry=0x7f5088000020, bytes=bytes@entry=2048) at malloc.c:3711
  #2  0x00007f509c8e6412 in __GI___libc_malloc (bytes=2048) at malloc.c:3073
  #3  0x00007f509d6e925e in g_realloc (mem=0x0, n_bytes=2048) at gmem.c:164
  #4  0x00007f509d705a57 in g_string_maybe_expand (string=string@entry=0x7f5088001f20, len=len@entry=1024) at gstring.c:102
  #5  0x00007f509d705ab6 in g_string_sized_new (dfl_size=dfl_size@entry=1024) at gstring.c:127
  #6  0x00007f509d708c5e in g_test_log_dump (len=<synthetic pointer>, msg=<synthetic pointer>) at gtestutils.c:3330
  #7  0x00007f509d708c5e in g_test_log
      (lbit=G_TEST_LOG_ERROR, string1=0x7f508800fcb0 "GLib:ERROR:ghash.c:377:g_hash_table_lookup_node: assertion failed: (hash_table->ref_count > 0)", string2=<optimized out>, n_args=0, largs=0x0) at gtestutils.c:975
  #8  0x00007f509d70af2a in g_assertion_message
      (domain=<optimized out>, file=0x7f509d7324a2 "ghash.c", line=<optimized out>, func=0x7f509d732750 <__func__.11348> "g_hash_table_lookup_node", message=<optimized out>)
      at gtestutils.c:2504
  #9  0x00007f509d70af8e in g_assertion_message_expr
      (domain=domain@entry=0x7f509d72d76e "GLib", file=file@entry=0x7f509d7324a2 "ghash.c", line=line@entry=377, func=func@entry=0x7f509d732750 <__func__.11348> "g_hash_table_lookup_node", expr=expr@entry=0x7f509d732488 "hash_table->ref_count > 0") at gtestutils.c:2555
  #10 0x00007f509d6d197e in g_hash_table_lookup_node (hash_table=0x55b70ace1760, key=<optimized out>, hash_return=<synthetic pointer>) at ghash.c:377
  #11 0x00007f509d6d197e in g_hash_table_lookup_node (hash_return=<synthetic pointer>, key=<optimized out>, hash_table=0x55b70ace1760) at ghash.c:361
  #12 0x00007f509d6d197e in g_hash_table_remove_internal (hash_table=0x55b70ace1760, key=<optimized out>, notify=1) at ghash.c:1371
  #13 0x00007f509d6e0664 in g_source_unref_internal (source=0x7f5088000b60, context=0x55b70ad87e00, have_lock=0) at gmain.c:2103
  #14 0x00007f509d6e1f64 in g_source_unref (source=<optimized out>) at gmain.c:2176
  #15 0x00007f50a08ff84c in glib_autoptr_cleanup_GSource (_ptr=<synthetic pointer>) at /usr/include/glib-2.0/glib/glib-autocleanups.h:58
  #16 0x00007f50a08ff84c in virEventThreadWorker (opaque=0x55b70ad87f80) at ../../src/util/vireventthread.c:114
  #17 0x00007f509d70bd4a in g_thread_proxy (data=0x55b70acf3850) at gthread.c:784
  #18 0x00007f509d04714a in start_thread (arg=<optimized out>) at pthread_create.c:479
  #19 0x00007f509c95cf23 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

  Thread 1 (Thread 0x7f50a1380c00 (LWP 222802)):
  #0  0x00007f509c8977ff in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
  #1  0x00007f509c881c35 in __GI_abort () at abort.c:79
  #2  0x00007f509d72a823 in g_mutex_clear (mutex=0x55b70ad87e00) at gthread-posix.c:1307
  #3  0x00007f509d72a823 in g_mutex_clear (mutex=mutex@entry=0x55b70ad87e00) at gthread-posix.c:1302
  #4  0x00007f509d6e1a84 in g_main_context_unref (context=0x55b70ad87e00) at gmain.c:582
  #5  0x00007f509d6e1a84 in g_main_context_unref (context=0x55b70ad87e00) at gmain.c:541
  #6  0x00007f50a08ffabb in vir_event_thread_finalize (object=0x55b70ad83180 [virEventThread]) at ../../src/util/vireventthread.c:50
  #7  0x00007f509d9c48a9 in g_object_unref (_object=<optimized out>) at gobject.c:3340
  #8  0x00007f509d9c48a9 in g_object_unref (_object=0x55b70ad83180) at gobject.c:3232

  #9  0x00007f509583d311 in qemuProcessQMPFree (proc=proc@entry=0x55b70ad87b90) at ../../src/qemu/qemu_process.c:8355
  #10 0x00007f5095790f58 in virQEMUCapsInitQMPSingle
      (qemuCaps=qemuCaps@entry=0x55b70ad88010, libDir=libDir@entry=0x55b70ad049e0 "/tmp/virt-qemu-run-VZC9N0/lib/qemu", runUid=runUid@entry=107, runGid=runGid@entry=107, onlyTCG=onlyTCG@entry=false) at ../../src/qemu/qemu_capabilities.c:5409
  #11 0x00007f509579108f in virQEMUCapsInitQMP (runGid=107, runUid=107, libDir=0x55b70ad049e0 "/tmp/virt-qemu-run-VZC9N0/lib/qemu", qemuCaps=0x55b70ad88010)
      at ../../src/qemu/qemu_capabilities.c:5420
  #12 0x00007f509579108f in virQEMUCapsNewForBinaryInternal
      (hostArch=VIR_ARCH_X86_64, binary=binary@entry=0x55b70ad7dc40 "/usr/libexec/qemu-kvm", libDir=0x55b70ad049e0 "/tmp/virt-qemu-run-VZC9N0/lib/qemu", runUid=107, runGid=107, hostCPUSignature=0x55b70ad01320 "GenuineIntel, Intel(R) Xeon(R) Silver 4210 CPU @ 2.20GHz, family: 6, model: 85, stepping: 7", microcodeVersion=83898113, kernelVersion=0x55b70ad00d60 "4.18.0-211.el8.x86_64 #1 SMP Thu Jun 4 08:08:16 UTC 2020") at ../../src/qemu/qemu_capabilities.c:5472
  #13 0x00007f5095791373 in virQEMUCapsNewData (binary=0x55b70ad7dc40 "/usr/libexec/qemu-kvm", privData=0x55b70ad5b8f0) at ../../src/qemu/qemu_capabilities.c:5505
  #14 0x00007f50a09a32b1 in virFileCacheNewData (name=0x55b70ad7dc40 "/usr/libexec/qemu-kvm", cache=<optimized out>) at ../../src/util/virfilecache.c:208
  #15 0x00007f50a09a32b1 in virFileCacheValidate (cache=cache@entry=0x55b70ad5c030, name=name@entry=0x55b70ad7dc40 "/usr/libexec/qemu-kvm", data=data@entry=0x7ffca39ffd90)
      at ../../src/util/virfilecache.c:277
  #16 0x00007f50a09a37ea in virFileCacheLookup (cache=cache@entry=0x55b70ad5c030, name=name@entry=0x55b70ad7dc40 "/usr/libexec/qemu-kvm") at ../../src/util/virfilecache.c:310
  #17 0x00007f5095791627 in virQEMUCapsCacheLookup (cache=0x55b70ad5c030, binary=0x55b70ad7dc40 "/usr/libexec/qemu-kvm") at ../../src/qemu/qemu_capabilities.c:5647
  #18 0x00007f50957c34c3 in qemuDomainPostParseDataAlloc (def=<optimized out>, parseFlags=<optimized out>, opaque=<optimized out>, parseOpaque=0x7ffca39ffe18)
      at ../../src/qemu/qemu_domain.c:5470
  #19 0x00007f50a0a34051 in virDomainDefPostParse
      (def=def@entry=0x55b70ad7d200, parseFlags=parseFlags@entry=258, xmlopt=xmlopt@entry=0x55b70ad5d010, parseOpaque=parseOpaque@entry=0x0)
      at ../../src/conf/domain_conf.c:5970
  #20 0x00007f50a0a464bb in virDomainDefParseNode
      (xml=xml@entry=0x55b70aced140, root=root@entry=0x55b70ad5f020, xmlopt=xmlopt@entry=0x55b70ad5d010, parseOpaque=parseOpaque@entry=0x0, flags=flags@entry=258)
      at ../../src/conf/domain_conf.c:22520
  #21 0x00007f50a0a4669b in virDomainDefParse
      (xmlStr=xmlStr@entry=0x55b70ad5f9e0 "<domain type='kvm'>\n  <name>83</name>\n  <uuid>9350639d-1c8a-4f51-a4a6-4eaf8eabe83e</uuid>\n  <metadata>\n    <libosinfo:libosinfo xmlns:libosinfo=\"http://libosinfo.org/xmlns/libvirt/domain/1.0\">\n      <"..., filename=filename@entry=0x0, xmlopt=0x55b70ad5d010, parseOpaque=parseOpaque@entry=0x0, flags=flags@entry=258) at ../../src/conf/domain_conf.c:22474
  #22 0x00007f50a0a467ae in virDomainDefParseString
      (xmlStr=xmlStr@entry=0x55b70ad5f9e0 "<domain type='kvm'>\n  <name>83</name>\n  <uuid>9350639d-1c8a-4f51-a4a6-4eaf8eabe83e</uuid>\n  <metadata>\n    <libosinfo:libosinfo xmlns:libosinfo=\"http://libosinfo.org/xmlns/libvirt/domain/1.0\">\n      <"..., xmlopt=<optimized out>, parseOpaque=parseOpaque@entry=0x0, flags=flags@entry=258)
      at ../../src/conf/domain_conf.c:22488
  #23 0x00007f50958ce112 in qemuDomainCreateXML
      (conn=0x55b70acf9090, xml=0x55b70ad5f9e0 "<domain type='kvm'>\n  <name>83</name>\n  <uuid>9350639d-1c8a-4f51-a4a6-4eaf8eabe83e</uuid>\n  <metadata>\n    <libosinfo:libosinfo xmlns:libosinfo=\"http://libosinfo.org/xmlns/libvirt/domain/1.0\">\n      <"..., flags=0) at ../../src/qemu/qemu_driver.c:1744
  #24 0x00007f50a0c268ac in virDomainCreateXML
      (conn=0x55b70acf9090, xmlDesc=0x55b70ad5f9e0 "<domain type='kvm'>\n  <name>83</name>\n  <uuid>9350639d-1c8a-4f51-a4a6-4eaf8eabe83e</uuid>\n  <metadata>\n    <libosinfo:libosinfo xmlns:libosinfo=\"http://libosinfo.org/xmlns/libvirt/domain/1.0\">\n      <"..., flags=0) at ../../src/libvirt-domain.c:176
  #25 0x000055b709547e7b in main (argc=<optimized out>, argv=<optimized out>) at ../../src/qemu/qemu_shim.c:289

The solution is to explicitly unref the GSource at a safe time instead
of letting g_autoptr unref it when leaving scope.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2020-08-07 12:44:05 +01:00
.ctags.d maint: Add support for .ctags.d 2019-05-31 17:54:28 +02:00
.github github: skip lockdown of old issues/prs 2020-04-07 17:50:54 +01:00
build-aux build-aux: remove some syntax-check cruft 2020-08-04 16:44:56 +01:00
ci meson: update .gitlab-ci.yml file 2020-08-03 09:27:09 +02:00
docs docs/manpages/meson: fix sanlock detection 2020-08-05 13:32:59 +02:00
examples meson: examples: build and install example files 2020-08-03 09:27:06 +02:00
include meson: add include directory 2020-08-03 09:26:59 +02:00
po qemu: Separate out namespace handling code 2020-08-03 19:32:27 +02:00
scripts scripts: Fix meson-install-symlink.py overwriting existing links 2020-08-05 13:11:16 +02:00
src util: avoid race in releasing the GSource in event thread 2020-08-07 12:44:05 +01:00
tests tests: qemublocktest: fix crashing with SIGBUS 2020-08-04 20:19:48 +04:00
tools util: recommend g_strfreev instead of virStringListFree 2020-08-03 15:37:36 +02:00
.color_coded.in gnulib: delete all gnulib integration 2020-02-07 15:03:54 +00:00
.ctags ctags: Generate tags for headers, i.e. function prototypes 2018-09-18 14:21:33 +02:00
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.gitmodules gnulib: delete all gnulib integration 2020-02-07 15:03:54 +00:00
.gitpublish gitpublish: add a subject prefix 2020-01-16 13:04:11 +00:00
.mailmap mailmap: Remove some duplicates 2019-06-07 13:18:08 +02:00
.ycm_extra_conf.py.in gnulib: delete all gnulib integration 2020-02-07 15:03:54 +00:00
ABOUT-NLS Convert all remaining Markdown files to reStructuredText 2020-04-14 16:29:04 +02:00
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ChangeLog docs: point to GitLab as the primary git hosting 2020-06-03 13:38:33 +02:00
config.h config.h: add a copyright blurb 2020-08-03 13:54:15 +02:00
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CONTRIBUTING.rst meson: adjust our documentation to mention meson instead of autoconf 2020-08-03 09:27:09 +02:00
COPYING maint: follow recommended practice for using LGPL 2013-05-20 14:15:21 -06:00
COPYING.LESSER maint: Remove control characters from LGPL license file 2015-09-25 09:16:24 +02:00
gitdm.config gitdm: add 'ibm' file 2019-10-18 17:32:52 +02:00
libvirt-admin.pc.in Add libvirt-admin library 2015-06-16 13:46:20 +02:00
libvirt-lxc.pc.in Add pkg-config files for libvirt-qemu & libvirt-lxc 2014-06-23 16:17:27 +01:00
libvirt-qemu.pc.in Add pkg-config files for libvirt-qemu & libvirt-lxc 2014-06-23 16:17:27 +01:00
libvirt.pc.in Add pkg-config files for libvirt-qemu & libvirt-lxc 2014-06-23 16:17:27 +01:00
libvirt.spec.in meson: update spec file to use meson 2020-08-03 09:27:06 +02:00
meson_options.txt meson_options: change default value to auto for driver_esx 2020-08-04 11:25:51 +02:00
meson.build meson: fix readline detection if there is no pkg-config file 2020-08-05 13:32:59 +02:00
mingw-libvirt.spec.in spec: Require Fedora 31 2020-06-17 12:59:08 +02:00
NEWS.rst Post-release version bump to 6.7.0 2020-08-03 00:21:59 +02:00
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README 

.. image:: https://gitlab.com/libvirt/libvirt/badges/master/pipeline.svg
     :target: https://gitlab.com/libvirt/libvirt/pipelines
     :alt: GitLab CI Build Status
.. image:: https://bestpractices.coreinfrastructure.org/projects/355/badge
     :target: https://bestpractices.coreinfrastructure.org/projects/355
     :alt: CII Best Practices
.. image:: https://translate.fedoraproject.org/widgets/libvirt/-/libvirt/svg-badge.svg
     :target: https://translate.fedoraproject.org/engage/libvirt/
     :alt: Translation status

==============================
Libvirt API for virtualization
==============================

Libvirt provides a portable, long term stable C API for managing the
virtualization technologies provided by many operating systems. It
includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware
vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER
Hypervisor.

For some of these hypervisors, it provides a stateful management
daemon which runs on the virtualization host allowing access to the
API both by non-privileged local users and remote users.

Layered packages provide bindings of the libvirt C API into other
languages including Python, Perl, PHP, Go, Java, OCaml, as well as
mappings into object systems such as GObject, CIM and SNMP.

Further information about the libvirt project can be found on the
website:

https://libvirt.org


License
=======

The libvirt C API is distributed under the terms of GNU Lesser General
Public License, version 2.1 (or later). Some parts of the code that are
not part of the C library may have the more restrictive GNU General
Public License, version 2.0 (or later). See the files ``COPYING.LESSER``
and ``COPYING`` for full license terms & conditions.


Installation
============

Instructions on building and installing libvirt can be found on the website:

https://libvirt.org/compiling.html

Contributing
============

The libvirt project welcomes contributions in many ways. For most components
the best way to contribute is to send patches to the primary development
mailing list. Further guidance on this can be found on the website:

https://libvirt.org/contribute.html


Contact
=======

The libvirt project has two primary mailing lists:

* libvirt-users@redhat.com (**for user discussions**)
* libvir-list@redhat.com (**for development only**)

Further details on contacting the project are available on the website:

https://libvirt.org/contact.html