From f06f903d5cb3c14853a7213b6a70c078380b7a62 Mon Sep 17 00:00:00 2001 Message-Id: From: Michal Privoznik Date: Fri, 24 Jan 2020 15:05:50 +0100 Subject: [PATCH] qemu_conf: Avoid dereferencing NULL in virQEMUDriverGetHost{NUMACaps, CPU} When fixing [1] I've ran attached reproducer and had it spawn 1024 threads and query capabilities XML in each one of them. This lead libvirtd to hit the RLIMIT_NOFILE limit which was kind of expected. What wasn't expected was a subsequent segfault. It happened because virCPUProbeHost failed and returned NULL. We've taken the NULL and passed it to virCapabilitiesHostNUMARef() which dereferenced it. Code inspection showed the same flas in virQEMUDriverGetHostNUMACaps(), so I'm fixing both places. 1: https://bugzilla.redhat.com/show_bug.cgi?id=1791790 Signed-off-by: Michal Privoznik Reviewed-by: Peter Krempa (cherry picked from commit cc361a34c53210d682dbc5f2d506b4a23b71e399) https://bugzilla.redhat.com/show_bug.cgi?id=1794691 Signed-off-by: Michal Privoznik Message-Id: <5de22b27463cd2803b3910d7ef45a0e4bc08ad47.1579874719.git.mprivozn@redhat.com> Reviewed-by: Jiri Denemark --- src/qemu/qemu_conf.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c index 3d2f0e7bbb..e33ef4895e 100644 --- a/src/qemu/qemu_conf.c +++ b/src/qemu/qemu_conf.c @@ -1201,32 +1201,42 @@ virQEMUDriverCreateXMLConf(virQEMUDriverPtr driver, virCapsHostNUMAPtr virQEMUDriverGetHostNUMACaps(virQEMUDriverPtr driver) { + virCapsHostNUMAPtr hostnuma; + qemuDriverLock(driver); if (!driver->hostnuma) driver->hostnuma = virCapabilitiesHostNUMANewHost(); + hostnuma = driver->hostnuma; + qemuDriverUnlock(driver); - virCapabilitiesHostNUMARef(driver->hostnuma); + if (hostnuma) + virCapabilitiesHostNUMARef(hostnuma); - return driver->hostnuma; + return hostnuma; } virCPUDefPtr virQEMUDriverGetHostCPU(virQEMUDriverPtr driver) { + virCPUDefPtr hostcpu; + qemuDriverLock(driver); if (!driver->hostcpu) driver->hostcpu = virCPUProbeHost(virArchFromHost()); + hostcpu = driver->hostcpu; + qemuDriverUnlock(driver); - virCPUDefRef(driver->hostcpu); + if (hostcpu) + virCPUDefRef(hostcpu); - return driver->hostcpu; + return hostcpu; } -- 2.25.0