From 96518d4316b711c72205117f8d5c967d5127bbb6 Mon Sep 17 00:00:00 2001 Message-Id: <96518d4316b711c72205117f8d5c967d5127bbb6.1374788370.git.crobinso@redhat.com> From: Alex Jia 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=, context=) at rpc/virnetserver.c:326 #1 #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=, 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 Signed-off-by: Peter Krempa --- 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