[PATCH] net: ethernet: fix potential use-after-free in ec_bhf_remove

[PATCH] net: ethernet: fix potential use-after-free in ec_bhf_remove

[Pavel Skripkin]

static void ec_bhf_remove(struct pci_dev *dev)
{
...
	struct ec_bhf_priv *priv = netdev_priv(net_dev);

	unregister_netdev(net_dev);
	free_netdev(net_dev);

	pci_iounmap(dev, priv->dma_io);
	pci_iounmap(dev, priv->io);
...
}

priv is netdev private data, but it is used
after free_netdev(). It can cause use-after-free when accessing priv
pointer. So, fix it by moving free_netdev() after pci_iounmap()
calls.

Fixes: 6af55ff52b02 ("Driver for Beckhoff CX5020 EtherCAT master module.")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---
 drivers/net/ethernet/ec_bhf.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/ec_bhf.c b/drivers/net/ethernet/ec_bhf.c
index 46b0dbab8aad..7c992172933b 100644
--- a/drivers/net/ethernet/ec_bhf.c
+++ b/drivers/net/ethernet/ec_bhf.c
@@ -576,10 +576,12 @@ static void ec_bhf_remove(struct pci_dev *dev)
 	struct ec_bhf_priv *priv = netdev_priv(net_dev);
 
 	unregister_netdev(net_dev);
-	free_netdev(net_dev);
 
 	pci_iounmap(dev, priv->dma_io);
 	pci_iounmap(dev, priv->io);
+
+	free_netdev(net_dev);
+
 	pci_release_regions(dev);
 	pci_clear_master(dev);
 	pci_disable_device(dev);
-- 
2.32.0

Re: [PATCH] net: ethernet: fix potential use-after-free in ec_bhf_remove

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (refs/heads/master):

On Fri, 18 Jun 2021 16:49:02 +0300 you wrote:
> static void ec_bhf_remove(struct pci_dev *dev)
> {
> ...
> 	struct ec_bhf_priv *priv = netdev_priv(net_dev);
> 
> 	unregister_netdev(net_dev);
> 	free_netdev(net_dev);
> 
> [...]

Here is the summary with links:
  - net: ethernet: fix potential use-after-free in ec_bhf_remove
    https://git.kernel.org/netdev/net/c/9cca0c2d7014

You are awesome, thank you!
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