On 09/17/2014 10:25 AM, Peter Krempa wrote:
Live definition was used to look up the disk index while persistent one was indexed leading to a crash in qemuDomainGetBlockIoTune. Use the correct def and report a nice error.
Unfortunately it's accessible via read-only connection.
Mitigation - a read-only connection can only crash libvirtd in the cases where the guest is hot-plugging disks without reflecting those changes to the persistent definition. So avoiding hotplug, or doing hotplug where persistent is always modified alongside live definition, will avoid the out-of-bounds access.
Introduced in: eca96694a7f992be633d48d5ca03cedc9bbc3c9aa (v0.9.8) Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1140724 Reported-by: Luyao Huang <lhuang@redhat.com> Signed-off-by: Peter Krempa <pkrempa@redhat.com> --- src/qemu/qemu_driver.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
ACK. I can write up the libvirt security notice; we'll eventually need this backported to all the affected maint branches. I'll coordinate the backport effort with you on IRC.
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index a5a49ac..209c40e 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -16317,9 +16317,13 @@ qemuDomainGetBlockIoTune(virDomainPtr dom, }
if (flags & VIR_DOMAIN_AFFECT_CONFIG) { - int idx = virDomainDiskIndexByName(vm->def, disk, true); - if (idx < 0) + int idx = virDomainDiskIndexByName(persistentDef, disk, true); + if (idx < 0) { + virReportError(VIR_ERR_INVALID_ARG, + _("disk '%s' was not found in the domain config"), + disk); goto endjob; + } reply = persistentDef->disks[idx]->blkdeviotune; }
-- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org