[PATCH 6.18.y] virtio_net: atomically disable rx mode work

[Sasha Levin <sashal@kernel.org>]

From: Weiming Shi <bestswngs@gmail.com>

[ Upstream commit 1234707482053f1d1ac7c5756207d2c29057974c ]

virtio-net uses a boolean to gate rx_mode_work during device teardown.
The flag is changed under RTNL, but ndo_set_rx_mode checks it under the
address-list lock. A callback can therefore pass the check and enqueue work
after teardown has flushed it. The work is also enabled before late
probe operations that can fail, allowing probe unwind to free the netdev
with work still queued.

KASAN reports the worker using a virtqueue that probe unwind already freed:

  BUG: KASAN: slab-use-after-free in virtqueue_add_split
  Workqueue: events virtnet_rx_mode_work
  Call Trace:
   virtqueue_add_split (drivers/virtio/virtio_ring.c:706)
   virtqueue_add_sgs (drivers/virtio/virtio_ring.c:2839)
   virtnet_send_command_reply (drivers/net/virtio_net.c:3565)
   virtnet_rx_mode_work (drivers/net/virtio_net.c:3833)
   process_one_work (kernel/workqueue.c:3322)
   worker_thread (kernel/workqueue.c:3405)
  Freed by task 119:
   kfree (mm/slub.c:6625)
   vp_del_vq.isra.0 (drivers/virtio/virtio_pci_common.c:259)
   vp_del_vqs (drivers/virtio/virtio_pci_common.c:285)
   virtnet_probe (drivers/net/virtio_net.c:7129)

Use the workqueue disable mechanism to atomically reject new queue attempts
and drain running work. Keep work disabled until probe succeeds or restore
has reattached the netdev, then enable it and replay receive-mode state for
a running interface. Disable it before resource teardown in freeze and
remove.

Fixes: b9f7425239a0 ("virtio-net: convert rx mode setting to use workqueue")
Cc: stable@vger.kernel.org
Reported-by: <co+d17c2bc750a9cbbb@bugs.sh>
Assisted-by: LLM
Signed-off-by: Weiming Shi <bestswngs@gmail.com>
Link: https://patch.msgid.link/20261017114237.2786302-2-bestswngs@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
[ sashal: Adjusted context to preserve existing refill handling and restore error paths. ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/virtio_net.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index b7ab57f4e277a..34390befdf8a8 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -458,9 +458,6 @@ struct virtnet_info {
 	/* Work struct for setting rx mode */
 	struct work_struct rx_mode_work;
 
-	/* OK to queue work setting RX mode? */
-	bool rx_mode_work_enabled;
-
 	/* Does the affinity hint is set for virtqueues? */
 	bool affinity_hint_set;
 
@@ -740,16 +737,13 @@ static void disable_delayed_refill(struct virtnet_info *vi)
 
 static void enable_rx_mode_work(struct virtnet_info *vi)
 {
-	rtnl_lock();
-	vi->rx_mode_work_enabled = true;
-	rtnl_unlock();
+	if (enable_work(&vi->rx_mode_work) && netif_running(vi->dev))
+		schedule_work(&vi->rx_mode_work);
 }
 
 static void disable_rx_mode_work(struct virtnet_info *vi)
 {
-	rtnl_lock();
-	vi->rx_mode_work_enabled = false;
-	rtnl_unlock();
+	disable_work_sync(&vi->rx_mode_work);
 }
 
 static void virtqueue_napi_schedule(struct napi_struct *napi,
@@ -3996,8 +3990,7 @@ static void virtnet_set_rx_mode(struct net_device *dev)
 {
 	struct virtnet_info *vi = netdev_priv(dev);
 
-	if (vi->rx_mode_work_enabled)
-		schedule_work(&vi->rx_mode_work);
+	schedule_work(&vi->rx_mode_work);
 }
 
 static int virtnet_vlan_rx_add_vid(struct net_device *dev,
@@ -5813,7 +5806,6 @@ static void virtnet_freeze_down(struct virtio_device *vdev)
 	/* Make sure no work handler is accessing the device */
 	flush_work(&vi->config_work);
 	disable_rx_mode_work(vi);
-	flush_work(&vi->rx_mode_work);
 
 	if (netif_running(vi->dev)) {
 		rtnl_lock();
@@ -5840,7 +5832,6 @@ static int virtnet_restore_up(struct virtio_device *vdev)
 	virtio_device_ready(vdev);
 
 	enable_delayed_refill(vi);
-	enable_rx_mode_work(vi);
 
 	if (netif_running(vi->dev)) {
 		rtnl_lock();
@@ -5853,6 +5844,8 @@ static int virtnet_restore_up(struct virtio_device *vdev)
 	netif_tx_lock_bh(vi->dev);
 	netif_device_attach(vi->dev);
 	netif_tx_unlock_bh(vi->dev);
+
+	enable_rx_mode_work(vi);
 	return err;
 }
 
@@ -6952,6 +6945,7 @@ static int virtnet_probe(struct virtio_device *vdev)
 
 	INIT_WORK(&vi->config_work, virtnet_config_changed_work);
 	INIT_WORK(&vi->rx_mode_work, virtnet_rx_mode_work);
+	disable_work(&vi->rx_mode_work);
 	spin_lock_init(&vi->refill_lock);
 
 	if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF)) {
@@ -7103,8 +7097,6 @@ static int virtnet_probe(struct virtio_device *vdev)
 	if (vi->has_rss || vi->has_rss_hash_report)
 		virtnet_init_default_rss(vi);
 
-	enable_rx_mode_work(vi);
-
 	/* serialize netdev register + virtio_device_ready() with ndo_open() */
 	rtnl_lock();
 
@@ -7204,6 +7196,8 @@ static int virtnet_probe(struct virtio_device *vdev)
 		goto free_unregister_netdev;
 	}
 
+	enable_rx_mode_work(vi);
+
 	pr_debug("virtnet: registered device %s with %d RX and TX vq's\n",
 		 dev->name, max_queue_pairs);
 
@@ -7255,7 +7249,6 @@ static void virtnet_remove(struct virtio_device *vdev)
 	/* Make sure no work handler is accessing the device. */
 	flush_work(&vi->config_work);
 	disable_rx_mode_work(vi);
-	flush_work(&vi->rx_mode_work);
 
 	virtnet_free_irq_moder(vi);
 
-- 
2.53.0