[SRU][F][PATCH 1/2] eth: sungem: remove .ndo_poll_controller to avoid deadlocks

[Massimiliano Pellizzer]

From: Jakub Kicinski <kuba at kernel.org>

Erhard reports netpoll warnings from sungem:

  netpoll_send_skb_on_dev(): eth0 enabled interrupts in poll (gem_start_xmit+0x0/0x398)
  WARNING: CPU: 1 PID: 1 at net/core/netpoll.c:370 netpoll_send_skb+0x1fc/0x20c

gem_poll_controller() disables interrupts, which may sleep.
We can't sleep in netpoll, it has interrupts disabled completely.
Strangely, gem_poll_controller() doesn't even poll the completions,
and instead acts as if an interrupt has fired so it just schedules
NAPI and exits. None of this has been necessary for years, since
netpoll invokes NAPI directly.

Fixes: fe09bb619096 ("sungem: Spring cleaning and GRO support")
Reported-and-tested-by: Erhard Furtner <erhard_f at mailbox.org>
Link: https://lore.kernel.org/all/20240428125306.2c3080ef@legion
Reviewed-by: Eric Dumazet <edumazet at google.com>
Link: https://lore.kernel.org/r/20240508134504.3560956-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba at kernel.org>
(backported from commit ac0a230f719b02432d8c7eba7615ebd691da86f4)
[mpellizzer: backported solving merge conflicts due to surrounding
instructions which do not affect the patch]
CVE-2024-38597
Signed-off-by: Massimiliano Pellizzer <massimiliano.pellizzer at canonical.com>
---
 drivers/net/ethernet/sun/sungem.c | 14 --------------
 1 file changed, 14 deletions(-)

diff --git a/drivers/net/ethernet/sun/sungem.c b/drivers/net/ethernet/sun/sungem.c
index 3e7631160384..73c6e1f821cf 100644
--- a/drivers/net/ethernet/sun/sungem.c
+++ b/drivers/net/ethernet/sun/sungem.c
@@ -959,17 +959,6 @@ static irqreturn_t gem_interrupt(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-#ifdef CONFIG_NET_POLL_CONTROLLER
-static void gem_poll_controller(struct net_device *dev)
-{
-	struct gem *gp = netdev_priv(dev);
-
-	disable_irq(gp->pdev->irq);
-	gem_interrupt(gp->pdev->irq, dev);
-	enable_irq(gp->pdev->irq);
-}
-#endif
-
 static void gem_tx_timeout(struct net_device *dev)
 {
 	struct gem *gp = netdev_priv(dev);
@@ -2835,9 +2824,6 @@ static const struct net_device_ops gem_netdev_ops = {
 	.ndo_change_mtu		= gem_change_mtu,
 	.ndo_validate_addr	= eth_validate_addr,
 	.ndo_set_mac_address    = gem_set_mac_address,
-#ifdef CONFIG_NET_POLL_CONTROLLER
-	.ndo_poll_controller    = gem_poll_controller,
-#endif
 };
 
 static int gem_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
-- 
2.43.0