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xfrm: Wait for RCU readers during policy netns exit

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xfrm_policy_fini() frees the policy_bydst hash tables after flushing the
policy work items and deleting all policies, but it does not wait for
concurrent RCU readers to leave their read-side critical sections first.

The policy_bydst tables are published via rcu_assign_pointer() and are
looked up through rcu_dereference_check(), so netns teardown must also
wait for an RCU grace period before freeing the table memory.

Fix this by adding synchronize_rcu() before freeing the policy hash tables.

Fixes: e1e551bc56 ("xfrm: policy: prepare policy_bydst hash for rcu lookups")
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Reviewed-by: Florian Westphal <fw@strlen.de>
This commit is contained in:
Steffen Klassert 2026-04-02 13:31:04 +02:00
parent 7081d46d32
commit 069daad4f2
1 changed files with 2 additions and 0 deletions
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2
net/xfrm/xfrm_policy.c
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@ -4290,6 +4290,8 @@ static void xfrm_policy_fini(struct net *net)
#endif
xfrm_policy_flush(net, XFRM_POLICY_TYPE_MAIN, false);
synchronize_rcu();
WARN_ON(!list_empty(&net->xfrm.policy_all));
for (dir = 0; dir < XFRM_POLICY_MAX; dir++) {