Re: [libvirt] [PATCH] daemon: Fix crash in virTypedParameterArrayClear

Daemon uses the following pattern when dispatching APIs with typed parameters: VIR_ALLOC_N(params, nparams); virDomain*(dom, params,&nparams, flags); virTypedParameterArrayClear(params, nparams); In case nparams was originally set to 0, virDomain* API would fill it with the number of typed parameters it can provide and we would use this number (rather than zero) to clear params. Because VIR_ALLOC* returns non-NULL pointer even if size is 0, the code would end up walking through random memory. If we were lucky enough and the memory contained 7 (VIR_TYPED_PARAM_STRING) at the right place, we would try to free a random pointer and crash. Let's make sure params stays NULL when nparams is 0. --- daemon/remote.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/daemon/remote.c b/daemon/remote.c index 80626a2..d25717c 100644 --- a/daemon/remote.c +++ b/daemon/remote.c @@ -989,7 +989,7 @@ remoteDispatchDomainGetSchedulerParameters(virNetServerPtr server ATTRIBUTE_UNUS virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("nparams too large")); goto cleanup; } - if (VIR_ALLOC_N(params, nparams)< 0) + if (nparams&& VIR_ALLOC_N(params, nparams)< 0) goto no_memory; if (!(dom = get_nonnull_domain(priv->conn, args->dom))) @@ -1098,7 +1098,7 @@ remoteDispatchDomainGetSchedulerParametersFlags(virNetServerPtr server ATTRIBUTE virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("nparams too large")); goto cleanup; } - if (VIR_ALLOC_N(params, nparams)< 0) + if (nparams&& VIR_ALLOC_N(params, nparams)< 0)