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qemu: Avoid double free of VM

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One of my previous patches (c7ac2519b7) did try to fix the issue when
domain dies too soon during migration. However, this clumsy approach was
missing removal of qemuProcessHandleMonitorDestroy resulting in double
unrefing of mon->vm and hence producing the daemon crash:

==11843== Invalid read of size 4
==11843==    at 0x50C28C5: virObjectUnref (virobject.c:255)
==11843==    by 0x1148F7DB: qemuMonitorDispose (qemu_monitor.c:258)
==11843==    by 0x50C2991: virObjectUnref (virobject.c:262)
==11843==    by 0x50C2D13: virObjectFreeCallback (virobject.c:388)
==11843==    by 0x509C37B: virEventPollCleanupHandles (vireventpoll.c:583)
==11843==    by 0x509C711: virEventPollRunOnce (vireventpoll.c:652)
==11843==    by 0x509A620: virEventRunDefaultImpl (virevent.c:274)
==11843==    by 0x520D21C: virNetServerRun (virnetserver.c:1112)
==11843==    by 0x11F368: main (libvirtd.c:1513)
==11843==  Address 0x13b88864 is 4 bytes inside a block of size 136 free'd
==11843==    at 0x4A07F5C: free (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==11843==    by 0x5079A2F: virFree (viralloc.c:580)
==11843==    by 0x50C29E3: virObjectUnref (virobject.c:270)
==11843==    by 0x114770E4: qemuProcessHandleMonitorDestroy (qemu_process.c:1103)
==11843==    by 0x1148F7CB: qemuMonitorDispose (qemu_monitor.c:257)
==11843==    by 0x50C2991: virObjectUnref (virobject.c:262)
==11843==    by 0x50C2D13: virObjectFreeCallback (virobject.c:388)
==11843==    by 0x509C37B: virEventPollCleanupHandles (vireventpoll.c:583)
==11843==    by 0x509C711: virEventPollRunOnce (vireventpoll.c:652)
==11843==    by 0x509A620: virEventRunDefaultImpl (virevent.c:274)
==11843==    by 0x520D21C: virNetServerRun (virnetserver.c:1112)
==11843==    by 0x11F368: main (libvirtd.c:1513)

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
This commit is contained in:
Michal Privoznik
2013-11-06 11:38:58 +01:00
parent eab51940bd
commit 5a4c2374a2
1 changed files with 3 additions and 13 deletions
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16
src/qemu/qemu_process.c
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@@ -1095,14 +1095,6 @@ error:
return -1;
}
static void qemuProcessHandleMonitorDestroy(qemuMonitorPtr mon ATTRIBUTE_UNUSED,
virDomainObjPtr vm,
void *opaque ATTRIBUTE_UNUSED)
{
virObjectUnref(vm);
}
static int
qemuProcessHandleTrayChange(qemuMonitorPtr mon ATTRIBUTE_UNUSED,
virDomainObjPtr vm,
@@ -1366,7 +1358,6 @@ cleanup:
static qemuMonitorCallbacks monitorCallbacks = {
.destroy = qemuProcessHandleMonitorDestroy,
.eofNotify = qemuProcessHandleMonitorEOF,
.errorNotify = qemuProcessHandleMonitorError,
.diskSecretLookup = qemuProcessFindVolumeQcowPassphrase,
@@ -1403,7 +1394,7 @@ qemuConnectMonitor(virQEMUDriverPtr driver, virDomainObjPtr vm, int logfd)
}
/* Hold an extra reference because we can't allow 'vm' to be
* deleted while the monitor is active */
* deleted unitl the monitor gets its own reference. */
virObjectRef(vm);
ignore_value(virTimeMillisNow(&priv->monStart));
@@ -1419,11 +1410,10 @@ qemuConnectMonitor(virQEMUDriverPtr driver, virDomainObjPtr vm, int logfd)
ignore_value(qemuMonitorSetDomainLog(mon, logfd));
virObjectLock(vm);
virObjectUnref(vm);
priv->monStart = 0;
if (mon == NULL) {
virObjectUnref(vm);
} else if (!virDomainObjIsActive(vm)) {
if (!virDomainObjIsActive(vm)) {
qemuMonitorClose(mon);
mon = NULL;
}