[PATCH net v3 v3 3/3] macsec: use rcu_work to defer TX SA crypto cleanup out of softirq

[alexjlzheng@gmail.com]

From: Jinliang Zheng <alexjlzheng@tencent.com>

free_txsa() is an RCU callback running in softirq context, but calls
crypto_free_aead() which can invoke vunmap() internally on hardware
crypto drivers (e.g. hisi_sec2), triggering a kernel crash.

Use rcu_work to defer the cleanup to a workqueue, for the same reasons
as the analogous fix to free_rxsa() in the previous patch.

Fixes: c09440f7dcb3 ("macsec: introduce IEEE 802.1AE driver")
Signed-off-by: Jinliang Zheng <alexjlzheng@tencent.com>
---
 drivers/net/macsec.c | 8 +++++---
 include/net/macsec.h | 3 ++-
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c
index 67e4e3f439c7..e91d853c8d45 100644
--- a/drivers/net/macsec.c
+++ b/drivers/net/macsec.c
@@ -205,9 +205,10 @@ static struct macsec_tx_sa *macsec_txsa_get(struct macsec_tx_sa __rcu *ptr)
 	return sa;
 }
 
-static void free_txsa(struct rcu_head *head)
+static void free_txsa_work(struct work_struct *work)
 {
-	struct macsec_tx_sa *sa = container_of(head, struct macsec_tx_sa, rcu);
+	struct macsec_tx_sa *sa =
+		container_of(to_rcu_work(work), struct macsec_tx_sa, destroy_work);
 
 	crypto_free_aead(sa->key.tfm);
 	free_percpu(sa->stats);
@@ -217,7 +218,7 @@ static void free_txsa(struct rcu_head *head)
 static void macsec_txsa_put(struct macsec_tx_sa *sa)
 {
 	if (refcount_dec_and_test(&sa->refcnt))
-		call_rcu(&sa->rcu, free_txsa);
+		queue_rcu_work(macsec_wq, &sa->destroy_work);
 }
 
 static struct macsec_cb *macsec_skb_cb(struct sk_buff *skb)
@@ -1510,6 +1511,7 @@ static int init_tx_sa(struct macsec_tx_sa *tx_sa, char *sak, int key_len,
 	tx_sa->active = false;
 	refcount_set(&tx_sa->refcnt, 1);
 	spin_lock_init(&tx_sa->lock);
+	INIT_RCU_WORK(&tx_sa->destroy_work, free_txsa_work);
 
 	return 0;
 }
diff --git a/include/net/macsec.h b/include/net/macsec.h
index 0980ef36fbf0..d962093ee923 100644
--- a/include/net/macsec.h
+++ b/include/net/macsec.h
@@ -176,6 +176,7 @@ struct macsec_rx_sc {
  * @key: key structure
  * @ssci: short secure channel identifier
  * @stats: per-SA stats
+ * @destroy_work: deferred work to free the SA in process context after RCU grace period
  */
 struct macsec_tx_sa {
 	struct macsec_key key;
@@ -188,7 +189,7 @@ struct macsec_tx_sa {
 	refcount_t refcnt;
 	bool active;
 	struct macsec_tx_sa_stats __percpu *stats;
-	struct rcu_head rcu;
+	struct rcu_work destroy_work;
 };
 
 /**
-- 
2.39.3