2023-07-20 00:41:16

by Vladimir Oltean

Subject: [PATCH net] net: phy: prevent stale pointer dereference in phy_init()

mdio_bus_init() and phy_driver_register() both have error paths, and if
those are ever hit, ethtool will have a stale pointer to the
phy_ethtool_phy_ops stub structure, which references memory from a
module that failed to load (phylib).

It is probably hard to force an error in this code path even manually,
but the error teardown path of phy_init() should be the same as
phy_exit(), which is now simply not the case.

Fixes: 55d8f053ce1b ("net: phy: Register ethtool PHY operations")
Link: https://lore.kernel.org/netdev/[email protected]/
Suggested-by: Russell King (Oracle) <[email protected]>
Signed-off-by: Vladimir Oltean <[email protected]>
---
drivers/net/phy/phy_device.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 0c2014accba7..61921d4dbb13 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -3451,23 +3451,30 @@ static int __init phy_init(void)
{
int rc;

+ ethtool_set_ethtool_phy_ops(&phy_ethtool_phy_ops);
+
rc = mdio_bus_init();
if (rc)
- return rc;
+ goto err_ethtool_phy_ops;

- ethtool_set_ethtool_phy_ops(&phy_ethtool_phy_ops);
features_init();

rc = phy_driver_register(&genphy_c45_driver, THIS_MODULE);
if (rc)
- goto err_c45;
+ goto err_mdio_bus;

rc = phy_driver_register(&genphy_driver, THIS_MODULE);
- if (rc) {
- phy_driver_unregister(&genphy_c45_driver);
+ if (rc)
+ goto err_c45;
+
+ return 0;
+
err_c45:
- mdio_bus_exit();
- }
+ phy_driver_unregister(&genphy_c45_driver);
+err_mdio_bus:
+ mdio_bus_exit();
+err_ethtool_phy_ops:
+ ethtool_set_ethtool_phy_ops(NULL);

return rc;
}
--
2.34.1

2023-07-20 20:30:40

by patchwork-bot+netdevbpf

Subject: Re: [PATCH net] net: phy: prevent stale pointer dereference in phy_init()

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <[email protected]>:

On Thu, 20 Jul 2023 03:02:31 +0300 you wrote:
> mdio_bus_init() and phy_driver_register() both have error paths, and if
> those are ever hit, ethtool will have a stale pointer to the
> phy_ethtool_phy_ops stub structure, which references memory from a
> module that failed to load (phylib).
>
> It is probably hard to force an error in this code path even manually,
> but the error teardown path of phy_init() should be the same as
> phy_exit(), which is now simply not the case.
>
> [...]

Here is the summary with links:
- [net] net: phy: prevent stale pointer dereference in phy_init()
https://git.kernel.org/netdev/net/c/1c613beaf877

You are awesome, thank you!
--
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