On 2014-02-05 14:19, Jiri Denemark wrote:
If virDomainMemoryStats was run on a domain with virtio balloon driver running on an old qemu which supports QMP but does not support qom-list QMP command, libvirtd would crash. The reason is we did not check if qemuMonitorJSONGetObjectListPaths failed and moreover we even stored its result in an unsigned integer type.
Signed-off-by: Jiri Denemark <jdenemar@redhat.com> ---
Notes: version 2: - use signed type for i and j to avoid comparison between signed and unsigned types; gcc-- for not complaining about it
src/qemu/qemu_monitor.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c index a968901..a2769db 100644 --- a/src/qemu/qemu_monitor.c +++ b/src/qemu/qemu_monitor.c @@ -1019,7 +1019,7 @@ qemuMonitorFindBalloonObjectPath(qemuMonitorPtr mon, virDomainObjPtr vm, const char *curpath) { - size_t i, j, npaths = 0, nprops = 0; + ssize_t i, j, npaths = 0, nprops = 0; int ret = 0; char *nextpath = NULL; qemuMonitorJSONListPathPtr *paths = NULL; @@ -1045,6 +1045,8 @@ qemuMonitorFindBalloonObjectPath(qemuMonitorPtr mon, VIR_DEBUG("Searching for Balloon Object Path starting at %s", curpath);
npaths = qemuMonitorJSONGetObjectListPaths(mon, curpath, &paths); + if (npaths < 0) + return -1;
for (i = 0; i < npaths && ret == 0; i++) {
@@ -1061,6 +1063,11 @@ qemuMonitorFindBalloonObjectPath(qemuMonitorPtr mon, * then this version of qemu/kvm does not support the feature. */ nprops = qemuMonitorJSONGetObjectListPaths(mon, nextpath, &bprops); + if (nprops < 0) { + ret = -1; + goto cleanup; + } + for (j = 0; j < nprops; j++) { if (STREQ(bprops[j]->name, "guest-stats-polling-interval")) { VIR_DEBUG("Found Balloon Object Path %s", nextpath);
I tested this patch and so far it seems ok: libvirtd hasn't crashed during 1 hour. I'll leave it running during the night to be sure. I only see this now in the logs: 2014-02-05 14:54:41.280+0000: 8104: error : qemuMonitorJSONCheckError:354 : internal error: unable to execute QEMU command 'qom-list': The command qom-list has not been found 2014-02-05 14:54:41.306+0000: 8103: error : qemuMonitorJSONCheckError:354 : internal error: unable to execute QEMU command 'qom-list': The command qom-list has not been found 2014-02-05 14:54:41.333+0000: 8106: error : qemuMonitorJSONCheckError:354 : internal error: unable to execute QEMU command 'qom-list': The command qom-list has not been found 2014-02-05 14:54:41.358+0000: 8105: error : qemuMonitorJSONCheckError:354 : internal error: unable to execute QEMU command 'qom-list': The command qom-list has not been found but no crashes because of that. Franky