Hello,On Tue, 24 Mar 2026, Waiman Long wrote: > The ip_vs_ctl.c file and the associated ip_vs.h file are the only places > in the kernel where HK_TYPE_KTHREAD cpumask is being retrieved and used. > Now that HK_TYPE_KTHREAD/HK_TYPE_DOMAIN cpumask can be changed at run > time. We need to use RCU to guard access to this cpumask to avoid a > potential UAF problem as the returned cpumask may be freed before it > is being used. > > Signed-off-by: Waiman Long <[email protected]> > --- > include/net/ip_vs.h | 20 ++++++++++++++++---- > net/netfilter/ipvs/ip_vs_ctl.c | 13 ++++++++----- > 2 files changed, 24 insertions(+), 9 deletions(-) > > diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h > index 29a36709e7f3..17c85a575ef4 100644 > --- a/include/net/ip_vs.h > +++ b/include/net/ip_vs.h > @@ -1155,7 +1155,7 @@ static inline int sysctl_run_estimation(struct > netns_ipvs *ipvs) > return ipvs->sysctl_run_estimation; > } > > -static inline const struct cpumask *sysctl_est_cpulist(struct netns_ipvs > *ipvs) > +static inline const struct cpumask *__sysctl_est_cpulist(struct netns_ipvs > *ipvs) > { > if (ipvs->est_cpulist_valid) > return ipvs->sysctl_est_cpulist; > @@ -1273,7 +1273,7 @@ static inline int sysctl_run_estimation(struct > netns_ipvs *ipvs) > return 1; > } > > -static inline const struct cpumask *sysctl_est_cpulist(struct netns_ipvs > *ipvs) > +static inline const struct cpumask *__sysctl_est_cpulist(struct netns_ipvs > *ipvs) > { > return housekeeping_cpumask(HK_TYPE_KTHREAD); > } > @@ -1290,6 +1290,18 @@ static inline int sysctl_est_nice(struct netns_ipvs > *ipvs) > > #endif > May be there is little fuzz here, due to the recent changes in the nf-next tree. If this is a bugfix due to the missing RCU protection, may be you should add Fixes line too and use the nf tree. Probably, there will be fuzz/collisions with the changes in the nf-next tree... > +static inline bool sysctl_est_cpulist_empty(struct netns_ipvs *ipvs) > +{ > + guard(rcu)(); > + return cpumask_empty(__sysctl_est_cpulist(ipvs)); > +} > + > +static inline unsigned int sysctl_est_cpulist_weight(struct netns_ipvs *ipvs) > +{ > + guard(rcu)(); > + return cpumask_weight(__sysctl_est_cpulist(ipvs)); > +} > + > /* IPVS core functions > * (from ip_vs_core.c) > */ > @@ -1604,7 +1616,7 @@ static inline void ip_vs_est_stopped_recalc(struct > netns_ipvs *ipvs) > /* Stop tasks while cpulist is empty or if disabled with flag */ > ipvs->est_stopped = !sysctl_run_estimation(ipvs) || > (ipvs->est_cpulist_valid && > - cpumask_empty(sysctl_est_cpulist(ipvs))); > + sysctl_est_cpulist_empty(ipvs)); > #endif > } > > @@ -1620,7 +1632,7 @@ static inline bool ip_vs_est_stopped(struct netns_ipvs > *ipvs) > static inline int ip_vs_est_max_threads(struct netns_ipvs *ipvs) > { > unsigned int limit = IPVS_EST_CPU_KTHREADS * > - cpumask_weight(sysctl_est_cpulist(ipvs)); > + sysctl_est_cpulist_weight(ipvs); > > return max(1U, limit); > } > diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c > index 35642de2a0fe..f38a2e2a9dc5 100644 > --- a/net/netfilter/ipvs/ip_vs_ctl.c > +++ b/net/netfilter/ipvs/ip_vs_ctl.c > @@ -1973,11 +1973,14 @@ static int ipvs_proc_est_cpumask_get(const struct > ctl_table *table, > > mutex_lock(&ipvs->est_mutex); > > - if (ipvs->est_cpulist_valid) > - mask = *valp; > - else > - mask = (struct cpumask *)housekeeping_cpumask(HK_TYPE_KTHREAD); > - ret = scnprintf(buffer, size, "%*pbl\n", cpumask_pr_args(mask)); > + /* HK_TYPE_KTHREAD cpumask needs RCU protection */ Can we switch IPVS to use HK_TYPE_DOMAIN? The initial intention was to follow the code in kthread.c. Then you can reconsider if HK_TYPE_KTHREAD should be alias to HK_TYPE_DOMAIN, may be not if there are no other users... > + scoped_guard(rcu) { > + if (ipvs->est_cpulist_valid) > + mask = *valp; > + else > + mask = (struct cpumask > *)housekeeping_cpumask(HK_TYPE_KTHREAD); > + ret = scnprintf(buffer, size, "%*pbl\n", cpumask_pr_args(mask)); > + } > > mutex_unlock(&ipvs->est_mutex); > > -- > 2.53.0 Regards -- Julian Anastasov <[email protected]>
