[PATCH net] net: tn40xx: fix swnode use-after-free on probe failure

[PATCH net] net: tn40xx: fix swnode use-after-free on probe failure

[Johan Hovold]

The mdiobus allocated by tn40_mdiobus_init() has no primary firmware
node so its firmware node pointer points to the secondary software node
added by device_add_software_node() and whose reference is released by
device_remove_software_node().

Drop the stray firmware node reference decrement on probe failure and
driver unbind which leads to a use-after-free when deregistering the
software node group as the parent MDIO node has been freed before the
child PHY node.

Fixes: 25b6a6d29d40 ("net: tn40xx: create swnode for mdio and aqr105 phy and add to mdiobus")
Cc: stable@vger.kernel.org	# 6.15
Cc: Hans-Frieder Vogt <hfdevel@gmx.net>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/net/ethernet/tehuti/tn40_mdio.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/net/ethernet/tehuti/tn40_mdio.c b/drivers/net/ethernet/tehuti/tn40_mdio.c
index fb1a4a2e4dbc..49951477ac05 100644
--- a/drivers/net/ethernet/tehuti/tn40_mdio.c
+++ b/drivers/net/ethernet/tehuti/tn40_mdio.c
@@ -157,7 +157,6 @@ void tn40_swnodes_cleanup(struct tn40_priv *priv)
 {
 	/* cleanup of swnodes is only needed for AQR105-based cards */
 	if (priv->pdev->device == PCI_DEVICE_ID_TEHUTI_TN9510) {
-		fwnode_handle_put(dev_fwnode(&priv->mdio->dev));
 		device_remove_software_node(&priv->mdio->dev);
 		software_node_unregister_node_group(priv->nodes.group);
 	}
-- 
2.56.0

Re: [PATCH net] net: tn40xx: fix swnode use-after-free on probe failure

[netdev-bot+sinfo]

Hi!

This is an automated message. This series looks like a fix, but its
commit messages seem to be missing some information:

 - How the issue was discovered, e.g. hit in production, hit during
   development, syzbot report, manual code inspection, LLM or static
   analysis tool scan.

 - Whether the issue was actually triggered, or is only theoretical
   (e.g. found by code inspection). If it was triggered please include
   the symptoms, like the stack trace or error messages.

 - What hardware the change was tested on. For driver fixes please
   mention the device (and if relevant firmware version) used for
   testing, or say that the change was not tested on real hardware.

Please do not repost the series just to address the above. Instead,
reply to this email with the missing information, so that reviewers
can take it into account. If the series needs another revision for
other reasons, please include the information in the commit messages
then.

The evaluation is done by an LLM so it may be wrong, if you think
that is the case please reply and explain.

Re: [PATCH net] net: tn40xx: fix swnode use-after-free on probe failure

[Johan Hovold]

On Tue, Nov 10, 2026 at 10:06:52AM +0000, netdev-bot+sinfo@kernel.org wrote:

> This is an automated message. This series looks like a fix, but its
> commit messages seem to be missing some information:
> 
>  - How the issue was discovered, e.g. hit in production, hit during
>    development, syzbot report, manual code inspection, LLM or static
>    analysis tool scan.
>
>  - Whether the issue was actually triggered, or is only theoretical
>    (e.g. found by code inspection). If it was triggered please include
>    the symptoms, like the stack trace or error messages.
>
>  - What hardware the change was tested on. For driver fixes please
>    mention the device (and if relevant firmware version) used for
>    testing, or say that the change was not tested on real hardware.

This was found through inspection when reviewing users of
device_set_software_node() and has only been compile tested.

Johan