[libvirt] [PATCH 2/2] virPerfEventIsEnabled: Don't crash on shut off domains
So imagine the following. You connect read only to a daemon and
try to fetch stats for a shut off domain, e.g.:
virsh -r domstats $dom
but all of a sudden, virsh instead of printing the stats throws
the following error at you:
error: Disconnected from qemu:///system due to I/O error
error: End of file while reading data: Input/output error
The daemon crashed. This is its backtrace:
#0 0x00007fa43e3751a8 in virPerfEventIsEnabled (perf=0x0, type=VIR_PERF_EVENT_MBMT) at
util/virperf.c:241
#1 0x00007fa424a9f042 in qemuDomainGetStatsPerf (driver=0x7fa3f4022a30,
dom=0x7fa3f40e24c0, record=0x7fa41c000e20, maxparams=0x7fa4360b38d0, privflags=1) at
qemu/qemu_driver.c:19110
#2 0x00007fa424a9f2e7 in qemuDomainGetStats (conn=0x7fa41c001b20, dom=0x7fa3f40e24c0,
stats=127, record=0x7fa4360b3970, flags=1) at qemu/qemu_driver.c:19213
#3 0x00007fa424a9f672 in qemuConnectGetAllDomainStats (conn=0x7fa41c001b20,
doms=0x7fa41c0017f0, ndoms=1, stats=127, retStats=0x7fa4360b3a50, flags=0) at
qemu/qemu_driver.c:19303
#4 0x00007fa43e4e15f6 in virDomainListGetStats (doms=0x7fa41c0017f0, stats=0,
retStats=0x7fa4360b3a50, flags=0) at libvirt-domain.c:11615
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7f28d1a38700 (LWP 16154)]
0x00007f28da4fa1a8 in virPerfEventIsEnabled (perf=0x0, type=VIR_PERF_EVENT_MBMT) at
util/virperf.c:241
241 return event->enabled;
Problem is, shut off domains don't have priv->perf allocated.
Therefore if in frame #1 qemuDomainGetStatsPerf() tries to check
if perf events are enabled, NULL is passed to
virPerfEventIsEnabled() which due to some incredible
implementation dereference it. Fix this by checking whether
passed object is not NULL.
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
src/util/virperf.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/src/util/virperf.c b/src/util/virperf.c
index a0997f9..4661ba3 100644
--- a/src/util/virperf.c
+++ b/src/util/virperf.c
@@ -99,6 +99,9 @@ static virPerfEventPtr
virPerfGetEvent(virPerfPtr perf,
virPerfEventType type)
{
+ if (!perf)
+ return NULL;
+
if (type >= VIR_PERF_EVENT_LAST) {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("Event '%d' is not supported"),
--
2.8.3