macsec: use rcu_work to defer RX SA crypto cleanup out of softirq

crypto_free_aead() can internally invoke vunmap() (e.g. via
dma_free_attrs() in hardware crypto drivers such as hisi_sec2).
vunmap() must not be called from softirq context, but free_rxsa()
is an RCU callback that runs in softirq, leading to a kernel crash:

  vunmap+0x4c/0x70
  __iommu_dma_free+0xd0/0x138
  dma_free_attrs+0xf4/0x100
  sec_aead_exit+0x64/0xb8 [hisi_sec2]
  crypto_destroy_tfm+0x98/0x110
  free_rxsa+0x28/0x50 [macsec]
  rcu_do_batch+0x184/0x460
  rcu_core+0xf4/0x1f8
  handle_softirqs+0x118/0x330

Use rcu_work to defer the cleanup to a workqueue. rcu_work dispatches
the worker asynchronously after the RCU grace period, so no thread
blocks waiting, and concurrent releases of multiple SAs naturally
share the same grace period.

Fixes: c09440f7dcb3 ("macsec: introduce IEEE 802.1AE driver")
Signed-off-by: Jinliang Zheng <alexjlzheng@tencent.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Link: https://patch.msgid.link/20260511153102.2640368-3-alexjlzheng@tencent.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c
index ef5ac634f9163da72060dbbf0134dc4fea59fbed..e7ad24f1ea5b90a148e5cc14f3c1a0da2dbd55d2 100644 (file)
--- a/drivers/net/macsec.c
+++ b/drivers/net/macsec.c
@@ -176,9 +176,10 @@ static void macsec_rxsc_put(struct macsec_rx_sc *sc)
                call_rcu(&sc->rcu_head, free_rx_sc_rcu);
 }
 
-static void free_rxsa(struct rcu_head *head)
+static void free_rxsa_work(struct work_struct *work)
 {
-       struct macsec_rx_sa *sa = container_of(head, struct macsec_rx_sa, rcu);
+       struct macsec_rx_sa *sa =
+               container_of(to_rcu_work(work), struct macsec_rx_sa, destroy_work);
 
        crypto_free_aead(sa->key.tfm);
        free_percpu(sa->stats);
@@ -188,7 +189,7 @@ static void free_rxsa(struct rcu_head *head)
 static void macsec_rxsa_put(struct macsec_rx_sa *sa)
 {
        if (refcount_dec_and_test(&sa->refcnt))
-               call_rcu(&sa->rcu, free_rxsa);
+               queue_rcu_work(macsec_wq, &sa->destroy_work);
 }
 
 static struct macsec_tx_sa *macsec_txsa_get(struct macsec_tx_sa __rcu *ptr)
@@ -1409,6 +1410,7 @@ static int init_rx_sa(struct macsec_rx_sa *rx_sa, char *sak, int key_len,
        rx_sa->next_pn = 1;
        refcount_set(&rx_sa->refcnt, 1);
        spin_lock_init(&rx_sa->lock);
+       INIT_RCU_WORK(&rx_sa->destroy_work, free_rxsa_work);
 
        return 0;
 }

diff --git a/include/net/macsec.h b/include/net/macsec.h
index bc7de5b53e54319e3589b9bf67a7fdccd3197e7d..0980ef36fbf0a47582a2d9e363e41ed120e875fc 100644 (file)
--- a/include/net/macsec.h
+++ b/include/net/macsec.h
@@ -9,6 +9,7 @@
 
 #include <linux/u64_stats_sync.h>
 #include <linux/if_vlan.h>
+#include <linux/workqueue.h>
 #include <uapi/linux/if_link.h>
 #include <uapi/linux/if_macsec.h>
 
@@ -123,6 +124,7 @@ struct macsec_dev_stats {
  * @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_rx_sa {
        struct macsec_key key;
@@ -136,7 +138,7 @@ struct macsec_rx_sa {
        bool active;
        struct macsec_rx_sa_stats __percpu *stats;
        struct macsec_rx_sc *sc;
-       struct rcu_head rcu;
+       struct rcu_work destroy_work;
 };
 
 struct pcpu_rx_sc_stats {