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.
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Michal Privoznik 17f509a4d4 remoteClientCloseFunc: Don't mangle connection object refcount
Well, in 8ad126e6 we tried to fix a memory corruption problem.
However, the fix was not as good as it could be. I mean, the
commit has one line more than it should. I've noticed this output
just recently:

  # ./run valgrind --leak-check=full --show-reachable=yes ./tools/virsh domblklist gentoo
  ==17019== Memcheck, a memory error detector
  ==17019== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
  ==17019== Using Valgrind-3.10.1 and LibVEX; rerun with -h for copyright info
  ==17019== Command: /home/zippy/work/libvirt/libvirt.git/tools/.libs/virsh domblklist gentoo
  ==17019==
  Target     Source
  ------------------------------------------------
  fda        /var/lib/libvirt/images/fd.img
  vda        /var/lib/libvirt/images/gentoo.qcow2
  hdc        /home/zippy/tmp/install-amd64-minimal-20150402.iso

  ==17019== Thread 2:
  ==17019== Invalid read of size 4
  ==17019==    at 0x4EFF5B4: virObjectUnref (virobject.c:258)
  ==17019==    by 0x5038CFF: remoteClientCloseFunc (remote_driver.c:552)
  ==17019==    by 0x5069D57: virNetClientCloseLocked (virnetclient.c:685)
  ==17019==    by 0x506C848: virNetClientIncomingEvent (virnetclient.c:1852)
  ==17019==    by 0x5082136: virNetSocketEventHandle (virnetsocket.c:1913)
  ==17019==    by 0x4ECD64E: virEventPollDispatchHandles (vireventpoll.c:509)
  ==17019==    by 0x4ECDE02: virEventPollRunOnce (vireventpoll.c:658)
  ==17019==    by 0x4ECBF00: virEventRunDefaultImpl (virevent.c:308)
  ==17019==    by 0x130386: vshEventLoop (vsh.c:1864)
  ==17019==    by 0x4F1EB07: virThreadHelper (virthread.c:206)
  ==17019==    by 0xA8462D3: start_thread (in /lib64/libpthread-2.20.so)
  ==17019==    by 0xAB441FC: clone (in /lib64/libc-2.20.so)
  ==17019==  Address 0x139023f4 is 4 bytes inside a block of size 240 free'd
  ==17019==    at 0x4C2B1F0: free (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
  ==17019==    by 0x4EA8949: virFree (viralloc.c:582)
  ==17019==    by 0x4EFF6D0: virObjectUnref (virobject.c:273)
  ==17019==    by 0x4FE74D6: virConnectClose (libvirt.c:1390)
  ==17019==    by 0x13342A: virshDeinit (virsh.c:406)
  ==17019==    by 0x134A37: main (virsh.c:950)

The problem is, when registering remoteClientCloseFunc(), it's
conn->closeCallback which is ref'd. But in the function itself
it's conn->closeCallback->conn what is unref'd. This is causing
imbalance in reference counting. Moreover, there's no need for
the remote driver to increase/decrease conn refcount since it's
not used anywhere. It's just merely passed to client registered
callback. And for that purpose it's correctly ref'd in
virConnectRegisterCloseCallback() and then unref'd in
virConnectUnregisterCloseCallback().

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
(cherry picked from commit e689300770)
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
2015-09-03 17:46:15 +02:00
.gnulib@f39477dba7 maint: update to latest gnulib 2015-06-01 13:23:18 -06:00
build-aux bracket-spacing: Add syntax-check for unnecessary curly brackets 2014-11-14 17:13:36 +01:00
daemon admin: Tiny cleanups 2015-07-27 09:33:24 +02:00
docs Release of libvirt-1.2.18 2015-08-03 17:36:39 +08:00
examples Apparmor: allow reading block-rbd.so 2015-04-24 10:47:42 +02:00
gnulib maint: fix date in local gnulib patch 2015-01-05 16:44:10 +00:00
include qemu: Don't report false error from MigrateFinish 2015-07-10 11:47:13 +02:00
m4 virt-driver-vz: Require parallels-7.0.22 at least 2015-07-13 19:46:10 +03:00
po Release of libvirt-1.2.18 2015-08-03 17:36:39 +08:00
src remoteClientCloseFunc: Don't mangle connection object refcount 2015-09-03 17:46:15 +02:00
tests tests: Finish rename of the long nodeinfo test case 2015-07-27 08:22:24 +02:00
tools virsh: Refactor block job waiting in cmdBlockCopy 2015-07-21 15:32:59 +02:00
.ctags maint: Make ctags work out of the box 2013-07-18 08:47:21 +02:00
.dir-locals.el build: avoid tabs that failed syntax-check 2012-09-06 09:43:46 -06:00
.gitignore Revert "Example virt-admin" 2015-06-16 14:08:23 +02:00
.gitmodules
.mailmap maint: update .mailmap for recent contributions 2015-03-20 06:17:55 -06:00
AUTHORS.in AUTHORS: Add my email address to AUTHORS.in 2015-04-10 18:26:43 +03:00
autobuild.sh Disable libvirtd by default when building on Win32 2014-04-29 11:30:32 +01:00
autogen.sh maint: improve usage of autogen's --no-git 2015-02-06 11:35:29 -07:00
bootstrap maint: update to latest gnulib 2015-03-26 09:41:55 -06:00
bootstrap.conf Revert "bootstrap.conf: add check for flex" 2015-01-12 10:14:30 -07:00
cfg.mk Add support for admin API in libvirt daemon 2015-06-16 13:46:21 +02:00
ChangeLog-old Fix typos in src/* 2014-04-21 16:49:08 -06:00
config-post.h build: fix build of virt-login-shell on systems with older gnutls 2013-10-22 09:41:50 -06:00
configure.ac configure: clarify rationale for checking pkcheck 2015-07-22 10:50:49 +01:00
COPYING maint: follow recommended practice for using LGPL 2013-05-20 14:15:21 -06:00
COPYING.LESSER maint: follow recommended practice for using LGPL 2013-05-20 14:15:21 -06:00
HACKING maint: document use of zanata for translations 2015-06-10 15:26:44 -06:00
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 Release of libvirt-1.2.18 2015-08-03 17:36:39 +08:00
Makefile.am Temporarily disable admin API 2015-06-28 11:34:25 +08:00
Makefile.nonreentrant maint: use LGPL correctly 2013-05-20 14:03:48 -06:00
mingw-libvirt.spec.in parallels: substitute parallels with vz spec file and Makefile 2015-06-17 15:07:55 +03:00
README
README-hacking docs: update README-hacking 2014-05-06 16:20:24 -06:00
run.in Add PKG_CONFIG_PATH to run.in script. 2014-06-26 14:32:35 +01:00
TODO

         LibVirt : simple API for virtualization

  Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.

Daniel Veillard <veillard@redhat.com>