Commit 6624bba4 authored by Jinliang Zheng's avatar Jinliang Zheng Committed by Jakub Kicinski
Browse files

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: c09440f7 ("macsec: introduce IEEE 802.1AE driver")
Signed-off-by: default avatarJinliang Zheng <alexjlzheng@tencent.com>
Reviewed-by: default avatarSabrina Dubroca <sd@queasysnail.net>
Link: https://patch.msgid.link/20260511153102.2640368-3-alexjlzheng@tencent.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent c6690a90

drivers/net/macsec.c

+5 −3
Original line number Diff line number Diff line
@@ -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;

}

include/net/macsec.h

+3 −1
Original line number Diff line number Diff line
@@ -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 {