From 96518d4316b711c72205117f8d5c967d5127bbb6 Mon Sep 17 00:00:00 2001
Message-Id: <96518d4316b711c72205117f8d5c967d5127bbb6.1374788370.git.crobinso@redhat.com>
From: Alex Jia <ajia@redhat.com>
Date: Tue, 16 Jul 2013 17:30:20 +0800
Subject: [PATCH] qemu: Prevent crash of libvirtd without guest agent
configuration
If users haven't configured guest agent then qemuAgentCommand() will
dereference a NULL 'mon' pointer, which causes crash of libvirtd when
using agent based cpu (un)plug.
With the patch, when the qemu-ga service isn't running in the guest,
a expected error "error: Guest agent is not responding: Guest agent
not available for now" will be raised, and the error "error: argument
unsupported: QEMU guest agent is not configured" is raised when the
guest hasn't configured guest agent.
GDB backtrace:
(gdb) bt
#0 virNetServerFatalSignal (sig=11, siginfo=<value optimized out>, context=<value optimized out>) at rpc/virnetserver.c:326
#1 <signal handler called>
#2 qemuAgentCommand (mon=0x0, cmd=0x7f39300017b0, reply=0x7f394b090910, seconds=-2) at qemu/qemu_agent.c:975
#3 0x00007f39429507f6 in qemuAgentGetVCPUs (mon=0x0, info=0x7f394b0909b8) at qemu/qemu_agent.c:1475
#4 0x00007f39429d9857 in qemuDomainGetVcpusFlags (dom=<value optimized out>, flags=9) at qemu/qemu_driver.c:4849
#5 0x00007f3957dffd8d in virDomainGetVcpusFlags (domain=0x7f39300009c0, flags=8) at libvirt.c:9843
How to reproduce?
# To start a guest without guest agent configuration
# then run the following cmdline
# virsh vcpucount foobar --guest
error: End of file while reading data: Input/output error
error: One or more references were leaked after disconnect from the hypervisor
error: Failed to reconnect to the hypervisor
RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=984821
Signed-off-by: Alex Jia <ajia@redhat.com>
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
---
src/qemu/qemu_driver.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index b4a668a..95dd591 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -4122,6 +4122,19 @@ qemuDomainSetVcpusFlags(virDomainPtr dom, unsigned int nvcpus,
goto endjob;
}
+ if (priv->agentError) {
+ virReportError(VIR_ERR_AGENT_UNRESPONSIVE, "%s",
+ _("QEMU guest agent is not "
+ "available due to an error"));
+ goto endjob;
+ }
+
+ if (!priv->agent) {
+ virReportError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s",
+ _("QEMU guest agent is not configured"));
+ goto endjob;
+ }
+
qemuDomainObjEnterAgent(vm);
ncpuinfo = qemuAgentGetVCPUs(priv->agent, &cpuinfo);
qemuDomainObjExitAgent(vm);
@@ -4839,6 +4852,19 @@ qemuDomainGetVcpusFlags(virDomainPtr dom, unsigned int flags)
if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_QUERY) < 0)
goto cleanup;
+ if (priv->agentError) {
+ virReportError(VIR_ERR_AGENT_UNRESPONSIVE, "%s",
+ _("QEMU guest agent is not "
+ "available due to an error"));
+ goto endjob;
+ }
+
+ if (!priv->agent) {
+ virReportError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s",
+ _("QEMU guest agent is not configured"));
+ goto endjob;
+ }
+
if (!virDomainObjIsActive(vm)) {
virReportError(VIR_ERR_OPERATION_INVALID, "%s",
_("domain is not running"));
--
1.8.3.1