From bca4bfb9cc5c58cc26eb9c848a7cf4fcff963a01 Mon Sep 17 00:00:00 2001 From: Yizhou Zhao Date: Tue, 7 Jul 2026 19:00:14 +0800 Subject: [PATCH] netfilter: ecache: fix inverted time_after() check commit b06163ce52ec0561f202fbfb9b08090cb61f512e upstream. ecache_work_evict_list() redelivers DESTROY events for conntracks that were moved to the per-netns dying_list after event delivery failed. It sets a 10ms deadline: stop = jiffies + ECACHE_MAX_JIFFIES but then tests: time_after(stop, jiffies) This condition is true while the deadline is still in the future, so the worker returns STATE_RESTART after the first successful redelivery in the usual case. ecache_work() maps STATE_RESTART to delay 0, which turns the redelivery path into one dying conntrack per workqueue dispatch and makes the sent > 16 batching/cond_resched() path effectively unreachable. A conntrack netlink listener whose receive queue is congested can make DESTROY event delivery fail with -ENOBUFS. With sustained conntrack churn, entries then accumulate on the dying_list and are only drained at the degraded one-entry-per-dispatch rate once delivery succeeds again, wasting CPU on back-to-back workqueue reschedules and prolonging conntrack memory/resource pressure. In a KASAN QEMU test with CONFIG_NF_CONNTRACK_EVENTS=y and nf_conntrack.enable_hooks=1, a congested DESTROY listener caused 8192 nf_ct_delete() calls to return false and move entries to the dying_list. After closing the listener, the unfixed kernel needed 7670 ecache_work() entries to destroy 7669 conntracks. With this change, the same 8192 entries were destroyed by 2 ecache_work() entries. Swap the comparison so the worker restarts only after the deadline has expired. Fixes: 2ed3bf188b33 ("netfilter: ecache: use dedicated list for event redelivery") Cc: stable@vger.kernel.org Reported-by: Yizhou Zhao Reported-by: Yuxiang Yang Reported-by: Ao Wang Reported-by: Xuewei Feng Reported-by: Qi Li Reported-by: Ke Xu Assisted-by: Claude-Code:GLM-5.2 Signed-off-by: Yizhou Zhao Signed-off-by: Florian Westphal Signed-off-by: Greg Kroah-Hartman --- net/netfilter/nf_conntrack_ecache.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/netfilter/nf_conntrack_ecache.c b/net/netfilter/nf_conntrack_ecache.c index 6526bdcca580..efabee2063cc 100644 --- a/net/netfilter/nf_conntrack_ecache.c +++ b/net/netfilter/nf_conntrack_ecache.c @@ -77,7 +77,7 @@ next: hlist_nulls_del_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode); hlist_nulls_add_head(&ct->tuplehash[IP_CT_DIR_REPLY].hnnode, &evicted_list); - if (time_after(stop, jiffies)) { + if (time_after(jiffies, stop)) { ret = STATE_RESTART; break; }