[PATCH net 3/4] ovpn: run deferred work on a module-owned workqueue

[PATCH net 3/4] ovpn: run deferred work on a module-owned workqueue

[Antonio Quartulli]

From: Ralf Lici <ralf@mandelbit.com>

ovpn queues several work items whose callbacks execute module text.
These works currently run on the global system workqueues, so module
exit has no driver-owned drain point that guarantees the callbacks have
fully returned before the module text can be freed.

Object references protect the objects used by the callbacks, but they do
not prove that a workqueue function has returned. In particular, a
worker can drop the final reference that unblocks device teardown while
it is still executing ovpn code.

Add a module-owned workqueue and queue all ovpn work items on it. During
module exit, unregister rtnl and netlink first, flush the workqueue so
ordinary ovpn workers finish, run the final RCU barrier, and destroy the
workqueue last. This keeps the workqueue available for cleanup work
queued from RCU callbacks, while ensuring no ovpn work item can outlive
the module text.

The per-device delayed keepalive work remains explicitly disabled during
netdev teardown (disable_delayed_work_sync in ndo_uninit), since
flush_workqueue does not flush delayed work that is still only pending
on its timer.

Fixes: 3ecfd9349f40 ("ovpn: implement keepalive mechanism")
Fixes: 11851cbd60ea ("ovpn: implement TCP transport")
Signed-off-by: Ralf Lici <ralf@mandelbit.com>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
---
 drivers/net/ovpn/main.c     | 19 ++++++++++++++++++-
 drivers/net/ovpn/ovpnpriv.h |  4 ++++
 drivers/net/ovpn/peer.c     |  8 ++++----
 drivers/net/ovpn/tcp.c      |  9 ++++-----
 4 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ovpn/main.c b/drivers/net/ovpn/main.c
index 168cfe9b59a9..0d23a9d5ceb9 100644
--- a/drivers/net/ovpn/main.c
+++ b/drivers/net/ovpn/main.c
@@ -12,6 +12,7 @@
 #include <linux/module.h>
 #include <linux/netdevice.h>
 #include <linux/inetdevice.h>
+#include <linux/workqueue.h>
 #include <net/gro_cells.h>
 #include <net/ip.h>
 #include <net/rtnetlink.h>
@@ -26,6 +27,9 @@
 #include "tcp.h"
 #include "udp.h"
 
+/* module-owned workqueue on which all ovpn-specific work is queued */
+struct workqueue_struct *ovpn_wq;
+
 static void ovpn_priv_free(struct net_device *net)
 {
 	struct ovpn_priv *ovpn = netdev_priv(net);
@@ -264,10 +268,16 @@ static int __init ovpn_init(void)
 
 	ovpn_tcp_init();
 
+	ovpn_wq = alloc_workqueue("ovpn", 0, 0);
+	if (!ovpn_wq) {
+		pr_err("ovpn: cannot allocate workqueue\n");
+		return -ENOMEM;
+	}
+
 	err = rtnl_link_register(&ovpn_link_ops);
 	if (err) {
 		pr_err("ovpn: can't register rtnl link ops: %d\n", err);
-		return err;
+		goto destroy_wq;
 	}
 
 	err = ovpn_nl_register();
@@ -280,6 +290,9 @@ static int __init ovpn_init(void)
 
 unreg_rtnl:
 	rtnl_link_unregister(&ovpn_link_ops);
+destroy_wq:
+	destroy_workqueue(ovpn_wq);
+	ovpn_wq = NULL;
 	return err;
 }
 
@@ -288,7 +301,11 @@ static __exit void ovpn_cleanup(void)
 	ovpn_nl_unregister();
 	rtnl_link_unregister(&ovpn_link_ops);
 
+	flush_workqueue(ovpn_wq);
 	rcu_barrier();
+
+	destroy_workqueue(ovpn_wq);
+	ovpn_wq = NULL;
 }
 
 module_init(ovpn_init);
diff --git a/drivers/net/ovpn/ovpnpriv.h b/drivers/net/ovpn/ovpnpriv.h
index 5898f6adada7..84499140e4bd 100644
--- a/drivers/net/ovpn/ovpnpriv.h
+++ b/drivers/net/ovpn/ovpnpriv.h
@@ -15,6 +15,10 @@
 #include <uapi/linux/if_link.h>
 #include <uapi/linux/ovpn.h>
 
+struct workqueue_struct;
+
+extern struct workqueue_struct *ovpn_wq;
+
 /**
  * struct ovpn_peer_collection - container of peers for MultiPeer mode
  * @by_id: table of peers index by ID
diff --git a/drivers/net/ovpn/peer.c b/drivers/net/ovpn/peer.c
index b0519f9840d8..c95656ca7c35 100644
--- a/drivers/net/ovpn/peer.c
+++ b/drivers/net/ovpn/peer.c
@@ -62,7 +62,7 @@ void ovpn_peer_keepalive_set(struct ovpn_peer *peer, u32 interval, u32 timeout)
 	/* now that interval and timeout have been changed, kick
 	 * off the worker so that the next delay can be recomputed
 	 */
-	mod_delayed_work(system_percpu_wq, &peer->ovpn->keepalive_work, 0);
+	mod_delayed_work(ovpn_wq, &peer->ovpn->keepalive_work, 0);
 }
 
 /**
@@ -1371,7 +1371,7 @@ static time64_t ovpn_peer_keepalive_work_single(struct ovpn_peer *peer,
 			   peer->id);
 		if (WARN_ON(!ovpn_peer_hold(peer)))
 			return 0;
-		if (!schedule_work(&peer->keepalive_work))
+		if (!queue_work(ovpn_wq, &peer->keepalive_work))
 			ovpn_peer_put(peer);
 	}
 
@@ -1463,8 +1463,8 @@ void ovpn_peer_keepalive_work(struct work_struct *work)
 		netdev_dbg(ovpn->dev,
 			   "scheduling keepalive work: now=%llu next_run=%llu delta=%llu\n",
 			   next_run, now, next_run - now);
-		schedule_delayed_work(&ovpn->keepalive_work,
-				      (next_run - now) * HZ);
+		queue_delayed_work(ovpn_wq, &ovpn->keepalive_work,
+				   (next_run - now) * HZ);
 	}
 	unlock_ovpn(ovpn, &release_list);
 }
diff --git a/drivers/net/ovpn/tcp.c b/drivers/net/ovpn/tcp.c
index 0af14055c39a..8fe8a8e750a4 100644
--- a/drivers/net/ovpn/tcp.c
+++ b/drivers/net/ovpn/tcp.c
@@ -151,7 +151,7 @@ static void ovpn_tcp_rcv(struct strparser *strp, struct sk_buff *skb)
 	/* take reference for deferred peer deletion. should never fail */
 	if (WARN_ON(!ovpn_peer_hold(peer)))
 		goto err_nopeer;
-	if (!schedule_work(&peer->tcp.defer_del_work))
+	if (!queue_work(ovpn_wq, &peer->tcp.defer_del_work))
 		ovpn_peer_put(peer);
 	ovpn_dev_dstats_rx_dropped(peer->ovpn->dev);
 err_nopeer:
@@ -284,13 +284,12 @@ static void ovpn_tcp_send_sock(struct ovpn_peer *peer, struct sock *sk)
 			 * stream therefore we abort the connection
 			 */
 			ovpn_peer_hold(peer);
-			if (!schedule_work(&peer->tcp.defer_del_work))
+			if (!queue_work(ovpn_wq, &peer->tcp.defer_del_work))
 				ovpn_peer_put(peer);
 
 			/* we bail out immediately and keep tx_in_progress set
 			 * to true. This way we prevent more TX attempts
-			 * which would lead to more invocations of
-			 * schedule_work()
+			 * which would lead to more invocations of queue_work()
 			 */
 			return;
 		}
@@ -487,7 +486,7 @@ static void ovpn_tcp_write_space(struct sock *sk)
 	rcu_read_lock();
 	sock = rcu_dereference_sk_user_data(sk);
 	if (likely(sock && sock->peer)) {
-		schedule_work(&sock->tcp_tx_work);
+		queue_work(ovpn_wq, &sock->tcp_tx_work);
 		sock->peer->tcp.sk_cb.sk_write_space(sk);
 	}
 	rcu_read_unlock();
-- 
2.54.0

[PATCH net 0/4] pull request: fixes for ovpn 2026-08-09

[Antonio Quartulli]

Hi all!

This is a resend of the patchset from Aug 7th, with the
alloc_workqueue() warning fixed. I hope I am not too late!

This batch collects four ovpn fixes for net that I considered critical
enough. Anything else has been postponed to after the release (or will
directly go to net-next).

All patches in this set are from Ralf, addressing key-slot and workqueue
lifetime issues:
* a NULL dereference when killing a key that is not installed on the
  peer;
* crypto completion callbacks that could continue their cleanup after
  releasing the peer reference gating netdev and module teardown;
* deferred work running on the global workqueues with no driver-owned
  drain point at module exit;
* AEAD transforms being freed from an RCU callback even though
  crypto_free_aead() may sleep.

The series went through six rounds of sashiko pre-review on
openvpn-devel and should now be sashiko-free[tm].

Sashiko will still report pre-existing issues, but like I said above,
they are not critical and will be addressed later.


Please pull or let me know of any issue!

Thanks a lot,
	Antonio

The following changes since commit 594d905195024b228c962627ae5ae7c17bd582a4:

  af_unix: Unlink scc_entry in unix_del_edge(). (2026-08-06 11:52:48 -0700)

are available in the Git repository at:

  https://github.com/OpenVPN/ovpn-net-next.git tags/ovpn-net-20260809

for you to fetch changes up to 2da3dfa1ddfe55a065f484750c83660e3bd4ac00:

  ovpn: defer key slot crypto freeing to workqueue (2026-08-09 22:47:57 +0200)

----------------------------------------------------------------
Included fixes:
* release key slot crypto transforms from a workqueue rather than an RCU
  callback, because crypto_free_aead() may sleep with async or hardware
  implementations
* run all deferred ovpn work on a module-owned workqueue and drain it on
  module exit, so no work item can still be executing module text after
  the module is unloaded
* finish crypto callback cleanup (key slot release and leftover skb)
  before dropping the peer reference that gates netdev unregistration
  and module removal
* avoid dereferencing a NULL key slot when userspace asks to kill a key
  that is not installed on the peer

----------------------------------------------------------------
Ralf Lici (4):
      ovpn: fix NULL dereference when killing missing key
      ovpn: finish crypto callback cleanup before peer release
      ovpn: run deferred work on a module-owned workqueue
      ovpn: defer key slot crypto freeing to workqueue

 drivers/net/ovpn/crypto.c      | 26 +++++++++++---------------
 drivers/net/ovpn/crypto.h      |  4 +++-
 drivers/net/ovpn/crypto_aead.c | 19 ++++++++++++++-----
 drivers/net/ovpn/crypto_aead.h |  1 -
 drivers/net/ovpn/io.c          | 10 +++++-----
 drivers/net/ovpn/main.c        | 19 ++++++++++++++++++-
 drivers/net/ovpn/ovpnpriv.h    |  4 ++++
 drivers/net/ovpn/peer.c        |  8 ++++----
 drivers/net/ovpn/tcp.c         |  9 ++++-----
 9 files changed, 63 insertions(+), 37 deletions(-)

[PATCH net 1/4] ovpn: fix NULL dereference when killing missing key

[Antonio Quartulli]

From: Ralf Lici <ralf@mandelbit.com>

ovpn_crypto_kill_key assumes both crypto slots are populated and
dereferences each slot before checking it. That is not guaranteed: a
peer can have only one installed key, and the kill path may be asked to
remove a key that is not present.

Read each slot once while holding the crypto state lock, check for NULL
before looking at key_id, and only replace the slot that actually
matches.

Fixes: 89d3c0e4612a ("ovpn: kill key and notify userspace in case of IV exhaustion")
Signed-off-by: Ralf Lici <ralf@mandelbit.com>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
---
 drivers/net/ovpn/crypto.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ovpn/crypto.c b/drivers/net/ovpn/crypto.c
index 90580e32052f..2e95f29514fc 100644
--- a/drivers/net/ovpn/crypto.c
+++ b/drivers/net/ovpn/crypto.c
@@ -58,15 +58,19 @@ void ovpn_crypto_state_release(struct ovpn_crypto_state *cs)
 bool ovpn_crypto_kill_key(struct ovpn_crypto_state *cs, u8 key_id)
 {
 	struct ovpn_crypto_key_slot *ks = NULL;
+	struct ovpn_crypto_key_slot *tmp;
+	int slot = 0;
 
 	spin_lock_bh(&cs->lock);
-	if (rcu_access_pointer(cs->slots[0])->key_id == key_id) {
-		ks = rcu_replace_pointer(cs->slots[0], NULL,
-					 lockdep_is_held(&cs->lock));
-	} else if (rcu_access_pointer(cs->slots[1])->key_id == key_id) {
-		ks = rcu_replace_pointer(cs->slots[1], NULL,
-					 lockdep_is_held(&cs->lock));
+	tmp = rcu_access_pointer(cs->slots[slot]);
+	if (!tmp || tmp->key_id != key_id) {
+		slot = 1;
+		tmp = rcu_access_pointer(cs->slots[slot]);
 	}
+
+	if (tmp && tmp->key_id == key_id)
+		ks = rcu_replace_pointer(cs->slots[slot], NULL,
+					 lockdep_is_held(&cs->lock));
 	spin_unlock_bh(&cs->lock);
 
 	if (ks)
-- 
2.54.0

[PATCH net 2/4] ovpn: finish crypto callback cleanup before peer release

[Antonio Quartulli]

From: Ralf Lici <ralf@mandelbit.com>

Crypto completion callbacks hold both key-slot and peer references. The
peer reference pins the netdev, and dropping the last peer reference can
let netdev unregistration and module removal make progress.

Do not release that peer reference before the callback has finished its
own cleanup. If ovpn_crypto_key_slot_put runs after ovpn_peer_put, it can
schedule an RCU callback backed by module text after ovpn_cleanup
rcu_barrier has already run. The TX error path also freed the remaining
skb after ovpn_peer_put, leaving callback cleanup outside the peer/netdev
lifetime window.

Release the key slot and free any remaining skb first, then drop the peer
reference as the last callback action.

Fixes: 8534731dbf2d ("ovpn: implement packet processing")
Signed-off-by: Ralf Lici <ralf@mandelbit.com>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
---
 drivers/net/ovpn/io.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ovpn/io.c b/drivers/net/ovpn/io.c
index 9a66d693039a..9526f8096da6 100644
--- a/drivers/net/ovpn/io.c
+++ b/drivers/net/ovpn/io.c
@@ -204,10 +204,10 @@ void ovpn_decrypt_post(void *data, int ret)
 		ovpn_dev_dstats_rx_dropped(peer->ovpn->dev);
 	kfree_skb(skb);
 drop_nocount:
-	if (likely(peer))
-		ovpn_peer_put(peer);
 	if (likely(ks))
 		ovpn_crypto_key_slot_put(ks);
+	if (likely(peer))
+		ovpn_peer_put(peer);
 }
 
 /* RX path entry point: decrypt packet and forward it to the device */
@@ -302,11 +302,11 @@ void ovpn_encrypt_post(void *data, int ret)
 err:
 	if (unlikely(skb))
 		ovpn_dev_dstats_tx_dropped(peer->ovpn->dev);
-	if (likely(peer))
-		ovpn_peer_put(peer);
+	kfree_skb(skb);
 	if (likely(ks))
 		ovpn_crypto_key_slot_put(ks);
-	kfree_skb(skb);
+	if (likely(peer))
+		ovpn_peer_put(peer);
 }
 
 static bool ovpn_encrypt_one(struct ovpn_peer *peer, struct sk_buff *skb)
-- 
2.54.0

[PATCH net 3/4] ovpn: run deferred work on a module-owned workqueue

[Antonio Quartulli]

From: Ralf Lici <ralf@mandelbit.com>

ovpn queues several work items whose callbacks execute module text.
These works currently run on the global system workqueues, so module
exit has no driver-owned drain point that guarantees the callbacks have
fully returned before the module text can be freed.

Object references protect the objects used by the callbacks, but they do
not prove that a workqueue function has returned. In particular, a
worker can drop the final reference that unblocks device teardown while
it is still executing ovpn code.

Add a module-owned workqueue and queue all ovpn work items on it. During
module exit, unregister rtnl and netlink first, flush the workqueue so
ordinary ovpn workers finish, run the final RCU barrier, and destroy the
workqueue last. This keeps the workqueue available for cleanup work
queued from RCU callbacks, while ensuring no ovpn work item can outlive
the module text.

The per-device delayed keepalive work remains explicitly disabled during
netdev teardown (disable_delayed_work_sync in ndo_uninit), since
flush_workqueue does not flush delayed work that is still only pending
on its timer.

Fixes: 3ecfd9349f40 ("ovpn: implement keepalive mechanism")
Fixes: 11851cbd60ea ("ovpn: implement TCP transport")
Signed-off-by: Ralf Lici <ralf@mandelbit.com>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
---
 drivers/net/ovpn/main.c     | 19 ++++++++++++++++++-
 drivers/net/ovpn/ovpnpriv.h |  4 ++++
 drivers/net/ovpn/peer.c     |  8 ++++----
 drivers/net/ovpn/tcp.c      |  9 ++++-----
 4 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ovpn/main.c b/drivers/net/ovpn/main.c
index 168cfe9b59a9..0708249e9607 100644
--- a/drivers/net/ovpn/main.c
+++ b/drivers/net/ovpn/main.c
@@ -12,6 +12,7 @@
 #include <linux/module.h>
 #include <linux/netdevice.h>
 #include <linux/inetdevice.h>
+#include <linux/workqueue.h>
 #include <net/gro_cells.h>
 #include <net/ip.h>
 #include <net/rtnetlink.h>
@@ -26,6 +27,9 @@
 #include "tcp.h"
 #include "udp.h"
 
+/* module-owned workqueue on which all ovpn-specific work is queued */
+struct workqueue_struct *ovpn_wq;
+
 static void ovpn_priv_free(struct net_device *net)
 {
 	struct ovpn_priv *ovpn = netdev_priv(net);
@@ -264,10 +268,16 @@ static int __init ovpn_init(void)
 
 	ovpn_tcp_init();
 
+	ovpn_wq = alloc_workqueue("ovpn", WQ_PERCPU, 0);
+	if (!ovpn_wq) {
+		pr_err("ovpn: cannot allocate workqueue\n");
+		return -ENOMEM;
+	}
+
 	err = rtnl_link_register(&ovpn_link_ops);
 	if (err) {
 		pr_err("ovpn: can't register rtnl link ops: %d\n", err);
-		return err;
+		goto destroy_wq;
 	}
 
 	err = ovpn_nl_register();
@@ -280,6 +290,9 @@ static int __init ovpn_init(void)
 
 unreg_rtnl:
 	rtnl_link_unregister(&ovpn_link_ops);
+destroy_wq:
+	destroy_workqueue(ovpn_wq);
+	ovpn_wq = NULL;
 	return err;
 }
 
@@ -288,7 +301,11 @@ static __exit void ovpn_cleanup(void)
 	ovpn_nl_unregister();
 	rtnl_link_unregister(&ovpn_link_ops);
 
+	flush_workqueue(ovpn_wq);
 	rcu_barrier();
+
+	destroy_workqueue(ovpn_wq);
+	ovpn_wq = NULL;
 }
 
 module_init(ovpn_init);
diff --git a/drivers/net/ovpn/ovpnpriv.h b/drivers/net/ovpn/ovpnpriv.h
index 5898f6adada7..84499140e4bd 100644
--- a/drivers/net/ovpn/ovpnpriv.h
+++ b/drivers/net/ovpn/ovpnpriv.h
@@ -15,6 +15,10 @@
 #include <uapi/linux/if_link.h>
 #include <uapi/linux/ovpn.h>
 
+struct workqueue_struct;
+
+extern struct workqueue_struct *ovpn_wq;
+
 /**
  * struct ovpn_peer_collection - container of peers for MultiPeer mode
  * @by_id: table of peers index by ID
diff --git a/drivers/net/ovpn/peer.c b/drivers/net/ovpn/peer.c
index b0519f9840d8..c95656ca7c35 100644
--- a/drivers/net/ovpn/peer.c
+++ b/drivers/net/ovpn/peer.c
@@ -62,7 +62,7 @@ void ovpn_peer_keepalive_set(struct ovpn_peer *peer, u32 interval, u32 timeout)
 	/* now that interval and timeout have been changed, kick
 	 * off the worker so that the next delay can be recomputed
 	 */
-	mod_delayed_work(system_percpu_wq, &peer->ovpn->keepalive_work, 0);
+	mod_delayed_work(ovpn_wq, &peer->ovpn->keepalive_work, 0);
 }
 
 /**
@@ -1371,7 +1371,7 @@ static time64_t ovpn_peer_keepalive_work_single(struct ovpn_peer *peer,
 			   peer->id);
 		if (WARN_ON(!ovpn_peer_hold(peer)))
 			return 0;
-		if (!schedule_work(&peer->keepalive_work))
+		if (!queue_work(ovpn_wq, &peer->keepalive_work))
 			ovpn_peer_put(peer);
 	}
 
@@ -1463,8 +1463,8 @@ void ovpn_peer_keepalive_work(struct work_struct *work)
 		netdev_dbg(ovpn->dev,
 			   "scheduling keepalive work: now=%llu next_run=%llu delta=%llu\n",
 			   next_run, now, next_run - now);
-		schedule_delayed_work(&ovpn->keepalive_work,
-				      (next_run - now) * HZ);
+		queue_delayed_work(ovpn_wq, &ovpn->keepalive_work,
+				   (next_run - now) * HZ);
 	}
 	unlock_ovpn(ovpn, &release_list);
 }
diff --git a/drivers/net/ovpn/tcp.c b/drivers/net/ovpn/tcp.c
index 0af14055c39a..8fe8a8e750a4 100644
--- a/drivers/net/ovpn/tcp.c
+++ b/drivers/net/ovpn/tcp.c
@@ -151,7 +151,7 @@ static void ovpn_tcp_rcv(struct strparser *strp, struct sk_buff *skb)
 	/* take reference for deferred peer deletion. should never fail */
 	if (WARN_ON(!ovpn_peer_hold(peer)))
 		goto err_nopeer;
-	if (!schedule_work(&peer->tcp.defer_del_work))
+	if (!queue_work(ovpn_wq, &peer->tcp.defer_del_work))
 		ovpn_peer_put(peer);
 	ovpn_dev_dstats_rx_dropped(peer->ovpn->dev);
 err_nopeer:
@@ -284,13 +284,12 @@ static void ovpn_tcp_send_sock(struct ovpn_peer *peer, struct sock *sk)
 			 * stream therefore we abort the connection
 			 */
 			ovpn_peer_hold(peer);
-			if (!schedule_work(&peer->tcp.defer_del_work))
+			if (!queue_work(ovpn_wq, &peer->tcp.defer_del_work))
 				ovpn_peer_put(peer);
 
 			/* we bail out immediately and keep tx_in_progress set
 			 * to true. This way we prevent more TX attempts
-			 * which would lead to more invocations of
-			 * schedule_work()
+			 * which would lead to more invocations of queue_work()
 			 */
 			return;
 		}
@@ -487,7 +486,7 @@ static void ovpn_tcp_write_space(struct sock *sk)
 	rcu_read_lock();
 	sock = rcu_dereference_sk_user_data(sk);
 	if (likely(sock && sock->peer)) {
-		schedule_work(&sock->tcp_tx_work);
+		queue_work(ovpn_wq, &sock->tcp_tx_work);
 		sock->peer->tcp.sk_cb.sk_write_space(sk);
 	}
 	rcu_read_unlock();
-- 
2.54.0

[PATCH net 4/4] ovpn: defer key slot crypto freeing to workqueue

[Antonio Quartulli]

From: Ralf Lici <ralf@mandelbit.com>

Key slots are released through a kref and the existing release path
frees the AEAD transforms from an RCU callback. That is not safe for all
crypto implementations: crypto_free_aead can sleep, for example when an
async or hardware implementation has teardown work to complete.

Use queue_rcu_work for key-slot release. This keeps the RCU grace period
needed by lockless key-slot readers, but runs the actual crypto teardown
from workqueue context where sleeping is allowed. Once the rcu_work
callback runs, pre-existing RCU readers are gone, and the final kref put
already proves that no transform user remains, so the worker can release
the AEAD transforms and free the slot directly.

The previous patch drains ovpn_wq during module exit, so queued key-slot
teardown work cannot outlive module text.

Fixes: 8534731dbf2d ("ovpn: implement packet processing")
Signed-off-by: Ralf Lici <ralf@mandelbit.com>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
---
 drivers/net/ovpn/crypto.c      | 10 +---------
 drivers/net/ovpn/crypto.h      |  4 +++-
 drivers/net/ovpn/crypto_aead.c | 19 ++++++++++++++-----
 drivers/net/ovpn/crypto_aead.h |  1 -
 4 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/drivers/net/ovpn/crypto.c b/drivers/net/ovpn/crypto.c
index 2e95f29514fc..7e545428900a 100644
--- a/drivers/net/ovpn/crypto.c
+++ b/drivers/net/ovpn/crypto.c
@@ -18,20 +18,12 @@
 #include "crypto_aead.h"
 #include "crypto.h"
 
-static void ovpn_ks_destroy_rcu(struct rcu_head *head)
-{
-	struct ovpn_crypto_key_slot *ks;
-
-	ks = container_of(head, struct ovpn_crypto_key_slot, rcu);
-	ovpn_aead_crypto_key_slot_destroy(ks);
-}
-
 void ovpn_crypto_key_slot_release(struct kref *kref)
 {
 	struct ovpn_crypto_key_slot *ks;
 
 	ks = container_of(kref, struct ovpn_crypto_key_slot, refcount);
-	call_rcu(&ks->rcu, ovpn_ks_destroy_rcu);
+	queue_rcu_work(ovpn_wq, &ks->free_work);
 }
 
 /* can only be invoked when all peer references have been dropped (i.e. RCU
diff --git a/drivers/net/ovpn/crypto.h b/drivers/net/ovpn/crypto.h
index 0e284fec3a75..e3feb16d5498 100644
--- a/drivers/net/ovpn/crypto.h
+++ b/drivers/net/ovpn/crypto.h
@@ -10,6 +10,8 @@
 #ifndef _NET_OVPN_OVPNCRYPTO_H_
 #define _NET_OVPN_OVPNCRYPTO_H_
 
+#include <linux/workqueue.h>
+
 #include "pktid.h"
 #include "proto.h"
 
@@ -45,8 +47,8 @@ struct ovpn_crypto_key_slot {
 
 	struct ovpn_pktid_recv pid_recv ____cacheline_aligned_in_smp;
 	struct ovpn_pktid_xmit pid_xmit ____cacheline_aligned_in_smp;
+	struct rcu_work free_work;
 	struct kref refcount;
-	struct rcu_head rcu;
 };
 
 struct ovpn_crypto_state {
diff --git a/drivers/net/ovpn/crypto_aead.c b/drivers/net/ovpn/crypto_aead.c
index 8f07c418622b..74eaf6fac2f5 100644
--- a/drivers/net/ovpn/crypto_aead.c
+++ b/drivers/net/ovpn/crypto_aead.c
@@ -9,6 +9,7 @@
 
 #include <crypto/aead.h>
 #include <linux/skbuff.h>
+#include <linux/workqueue.h>
 #include <net/ip.h>
 #include <net/ipv6.h>
 #include <net/udp.h>
@@ -380,13 +381,19 @@ static struct crypto_aead *ovpn_aead_init(const char *title,
 	return ERR_PTR(ret);
 }
 
-void ovpn_aead_crypto_key_slot_destroy(struct ovpn_crypto_key_slot *ks)
+static void ovpn_aead_crypto_key_slot_free(struct ovpn_crypto_key_slot *ks)
 {
-	if (!ks)
-		return;
-
 	crypto_free_aead(ks->encrypt);
 	crypto_free_aead(ks->decrypt);
+}
+
+static void ovpn_aead_crypto_key_slot_free_work(struct work_struct *work)
+{
+	struct ovpn_crypto_key_slot *ks;
+
+	ks = container_of(to_rcu_work(work), struct ovpn_crypto_key_slot,
+			  free_work);
+	ovpn_aead_crypto_key_slot_free(ks);
 	kfree(ks);
 }
 
@@ -420,6 +427,7 @@ ovpn_aead_crypto_key_slot_new(const struct ovpn_key_config *kc)
 
 	ks->encrypt = NULL;
 	ks->decrypt = NULL;
+	INIT_RCU_WORK(&ks->free_work, ovpn_aead_crypto_key_slot_free_work);
 	kref_init(&ks->refcount);
 	ks->key_id = kc->key_id;
 
@@ -453,7 +461,8 @@ ovpn_aead_crypto_key_slot_new(const struct ovpn_key_config *kc)
 	return ks;
 
 destroy_ks:
-	ovpn_aead_crypto_key_slot_destroy(ks);
+	ovpn_aead_crypto_key_slot_free(ks);
+	kfree(ks);
 	return ERR_PTR(ret);
 }
 
diff --git a/drivers/net/ovpn/crypto_aead.h b/drivers/net/ovpn/crypto_aead.h
index 65a2ff307898..fae3b585a43b 100644
--- a/drivers/net/ovpn/crypto_aead.h
+++ b/drivers/net/ovpn/crypto_aead.h
@@ -22,7 +22,6 @@ int ovpn_aead_decrypt(struct ovpn_peer *peer, struct ovpn_crypto_key_slot *ks,
 
 struct ovpn_crypto_key_slot *
 ovpn_aead_crypto_key_slot_new(const struct ovpn_key_config *kc);
-void ovpn_aead_crypto_key_slot_destroy(struct ovpn_crypto_key_slot *ks);
 
 enum ovpn_cipher_alg ovpn_aead_crypto_alg(struct ovpn_crypto_key_slot *ks);
 
-- 
2.54.0