[PATCH 6.18 076/309] xfrm: prevent policy_hthresh.work from racing with netns teardown

Greg Kroah-Hartman
2026-03-31T16:59:53Z

From: Minwoo Ra <raminwo0202@gmail.com>

[ Upstream commit 29fe3a61bcdce398ee3955101c39f89c01a8a77e ]

A XFRM_MSG_NEWSPDINFO request can queue the per-net work item
policy_hthresh.work onto the system workqueue.

The queued callback, xfrm_hash_rebuild(), retrieves the enclosing
struct net via container_of(). If the net namespace is torn down
before that work runs, the associated struct net may already have
been freed, and xfrm_hash_rebuild() may then dereference stale memory.

xfrm_policy_fini() already flushes policy_hash_work during teardown,
but it does not synchronize policy_hthresh.work.

Synchronize policy_hthresh.work in xfrm_policy_fini() as well, so the
queued work cannot outlive the net namespace teardown and access a
freed struct net.

Fixes: 880a6fab8f6b ("xfrm: configure policy hash table thresholds by netlink")
Signed-off-by: Minwoo Ra <raminwo0202@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/xfrm/xfrm_policy.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 5428185196a1f..c32d34c441ee0 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -4282,6 +4282,8 @@ static void xfrm_policy_fini(struct net *net)
unsigned int sz;
int dir;

+ disable_work_sync(&net->xfrm.policy_hthresh.work);
+
flush_work(&net->xfrm.policy_hash_work);
#ifdef CONFIG_XFRM_SUB_POLICY
xfrm_policy_flush(net, XFRM_POLICY_TYPE_SUB, false);
--
2.51.0