From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org,
pabeni@redhat.com, edumazet@google.com, fw@strlen.de,
horms@kernel.org
Subject: [PATCH net 2/9] ipvs: clear the svc scheduler ptr early on edit
Date: Mon, 1 Jun 2026 13:59:16 +0200 [thread overview]
Message-ID: <20260601115923.433946-3-pablo@netfilter.org> (raw)
In-Reply-To: <20260601115923.433946-1-pablo@netfilter.org>
From: Julian Anastasov <ja@ssi.bg>
ip_vs_edit_service() while unbinding the old scheduler clears
the svc->scheduler ptr after the scheduler module initiates
RCU callbacks. This can cause packets to use the old
scheduler at the time when svc->sched_data is already freed
after RCU grace period.
Fix it by clearing the ptr early in ip_vs_unbind_scheduler(),
before the done_service method schedules any RCU callbacks.
Also, if the new scheduler fails to initialize when replacing
the old scheduler, try to restore the old scheduler while still
returning the error code.
Link: https://sashiko.dev/#/patchset/20260519015506.634185-1-rosenp%40gmail.com
Fixes: 05f00505a89a ("ipvs: fix crash if scheduler is changed")
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
include/net/ip_vs.h | 3 +--
net/netfilter/ipvs/ip_vs_ctl.c | 13 ++++++++-----
net/netfilter/ipvs/ip_vs_sched.c | 14 +++++++-------
3 files changed, 16 insertions(+), 14 deletions(-)
diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
index a02e569813d2..e517eaaa177b 100644
--- a/include/net/ip_vs.h
+++ b/include/net/ip_vs.h
@@ -1824,8 +1824,7 @@ int register_ip_vs_scheduler(struct ip_vs_scheduler *scheduler);
int unregister_ip_vs_scheduler(struct ip_vs_scheduler *scheduler);
int ip_vs_bind_scheduler(struct ip_vs_service *svc,
struct ip_vs_scheduler *scheduler);
-void ip_vs_unbind_scheduler(struct ip_vs_service *svc,
- struct ip_vs_scheduler *sched);
+void ip_vs_unbind_scheduler(struct ip_vs_service *svc);
struct ip_vs_scheduler *ip_vs_scheduler_get(const char *sched_name);
void ip_vs_scheduler_put(struct ip_vs_scheduler *scheduler);
struct ip_vs_conn *
diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index bd9cae44d214..16daba8cac83 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -1898,7 +1898,7 @@ ip_vs_add_service(struct netns_ipvs *ipvs, struct ip_vs_service_user_kern *u,
if (ret_hooks >= 0)
ip_vs_unregister_hooks(ipvs, u->af);
if (svc != NULL) {
- ip_vs_unbind_scheduler(svc, sched);
+ ip_vs_unbind_scheduler(svc);
ip_vs_service_free(svc);
}
ip_vs_scheduler_put(sched);
@@ -1962,9 +1962,8 @@ ip_vs_edit_service(struct ip_vs_service *svc, struct ip_vs_service_user_kern *u)
old_sched = rcu_dereference_protected(svc->scheduler, 1);
if (sched != old_sched) {
if (old_sched) {
- ip_vs_unbind_scheduler(svc, old_sched);
- RCU_INIT_POINTER(svc->scheduler, NULL);
- /* Wait all svc->sched_data users */
+ ip_vs_unbind_scheduler(svc);
+ /* Wait all svc->scheduler/sched_data users */
synchronize_rcu();
}
/* Bind the new scheduler */
@@ -1972,6 +1971,10 @@ ip_vs_edit_service(struct ip_vs_service *svc, struct ip_vs_service_user_kern *u)
ret = ip_vs_bind_scheduler(svc, sched);
if (ret) {
ip_vs_scheduler_put(sched);
+ /* Try to restore the old_sched */
+ if (old_sched &&
+ !ip_vs_bind_scheduler(svc, old_sched))
+ old_sched = NULL;
goto out;
}
}
@@ -2027,7 +2030,7 @@ static void __ip_vs_del_service(struct ip_vs_service *svc, bool cleanup)
/* Unbind scheduler */
old_sched = rcu_dereference_protected(svc->scheduler, 1);
- ip_vs_unbind_scheduler(svc, old_sched);
+ ip_vs_unbind_scheduler(svc);
ip_vs_scheduler_put(old_sched);
/* Unbind persistence engine, keep svc->pe */
diff --git a/net/netfilter/ipvs/ip_vs_sched.c b/net/netfilter/ipvs/ip_vs_sched.c
index c6e421c4e299..24adc38942a0 100644
--- a/net/netfilter/ipvs/ip_vs_sched.c
+++ b/net/netfilter/ipvs/ip_vs_sched.c
@@ -56,19 +56,19 @@ int ip_vs_bind_scheduler(struct ip_vs_service *svc,
/*
* Unbind a service with its scheduler
*/
-void ip_vs_unbind_scheduler(struct ip_vs_service *svc,
- struct ip_vs_scheduler *sched)
+void ip_vs_unbind_scheduler(struct ip_vs_service *svc)
{
- struct ip_vs_scheduler *cur_sched;
+ struct ip_vs_scheduler *sched;
- cur_sched = rcu_dereference_protected(svc->scheduler, 1);
- /* This check proves that old 'sched' was installed */
- if (!cur_sched)
+ sched = rcu_dereference_protected(svc->scheduler, 1);
+ if (!sched)
return;
+ /* Reset the scheduler before initiating any RCU callbacks */
+ rcu_assign_pointer(svc->scheduler, NULL);
+ smp_wmb(); /* paired with smp_rmb() in ip_vs_schedule() */
if (sched->done_service)
sched->done_service(svc);
- /* svc->scheduler can be set to NULL only by caller */
}
--
2.47.3
next prev parent reply other threads:[~2026-06-01 11:59 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-01 11:59 [PATCH net 0/9] Netfilter/IPVS fixes for net Pablo Neira Ayuso
2026-06-01 11:59 ` [PATCH net 1/9] netfilter: xt_NFQUEUE: prefer raw_smp_processor_id Pablo Neira Ayuso
2026-06-01 11:59 ` Pablo Neira Ayuso [this message]
2026-06-01 11:59 ` [PATCH net 3/9] netfilter: nft_fib_ipv6: bail out of sibling walk if rt got unlinked Pablo Neira Ayuso
2026-06-01 11:59 ` [PATCH net 4/9] netfilter: synproxy: add mutex to guard hook reference counting Pablo Neira Ayuso
2026-06-01 11:59 ` [PATCH net 5/9] netfilter: conntrack_irc: fix possible out-of-bounds read Pablo Neira Ayuso
2026-06-01 11:59 ` [PATCH net 6/9] netfilter: nft_tunnel: fix use-after-free on object destroy Pablo Neira Ayuso
2026-06-01 11:59 ` [PATCH net 7/9] netfilter: nft_ct: bail out on template ct in get eval Pablo Neira Ayuso
2026-06-01 11:59 ` [PATCH net 8/9] netfilter: bridge: make ebt_snat ARP rewrite writable Pablo Neira Ayuso
2026-06-01 11:59 ` [PATCH net 9/9] netfilter: nft_byteorder: remove multi-register support Pablo Neira Ayuso
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