netdev - [PATCH net] gve: prevent ethtool ops after shutdown

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Message-ID: <20250818211245.1156919-1-jeroendb@google.com>
Date: Mon, 18 Aug 2025 14:12:45 -0700
From: Jeroen de Borst <jeroendb@...gle.com>
To: netdev@...r.kernel.org
Cc: hramamurthy@...gle.com, davem@...emloft.net, edumazet@...gle.com, 
	kuba@...nel.org, willemb@...gle.com, pabeni@...hat.com, 
	Jordan Rhee <jordanrhee@...gle.com>, Jeroen de Borst <jeroendb@...gle.com>
Subject: [PATCH net] gve: prevent ethtool ops after shutdown

From: Jordan Rhee <jordanrhee@...gle.com>

A crash can occur if an ethtool operation is invoked
after shutdown() is called.

shutdown() is invoked during system shutdown to stop DMA operations
without performing expensive deallocations. It is discouraged to
unregister the netdev in this path, so the device may still be visible
to userspace and kernel helpers.

In gve, shutdown() tears down most internal data structures. If an
ethtool operation is dispatched after shutdown(), it will dereference
freed or NULL pointers, leading to a kernel panic. While graceful
shutdown normally quiesces userspace before invoking the reboot
syscall, forced shutdowns (as observed on GCP VMs) can still trigger
this path.

Fix by calling netif_device_detach() in shutdown().
This marks the device as detached so the ethtool ioctl handler
will skip dispatching operations to the driver.

Fixes: 974365e51861 ("gve: Implement suspend/resume/shutdown")
Signed-off-by: Jordan Rhee <jordanrhee@...gle.com>
Signed-off-by: Jeroen de Borst <jeroendb@...gle.com>
---
 drivers/net/ethernet/google/gve/gve_main.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
index 1f411d7..1be1b1e 100644
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -2870,6 +2870,8 @@ static void gve_shutdown(struct pci_dev *pdev)
 	struct gve_priv *priv = netdev_priv(netdev);
 	bool was_up = netif_running(priv->dev);

+	netif_device_detach(netdev);
+
 	rtnl_lock();
 	netdev_lock(netdev);
 	if (was_up && gve_close(priv->dev)) {
-- 
2.51.0.rc1.167.g924127e9c0-goog