[v1] net: usb: asix: validate PHY address before use

[PATCH] net: usb: asix: validate PHY address before use

Posted by Deepanshu Kartikey 1 month, 3 weeks ago

The ASIX driver reads the PHY address from the USB device via
asix_read_phy_addr(). A malicious or faulty device can return an
invalid address (>= PHY_MAX_ADDR), which causes a warning in
mdiobus_get_phy():

  addr 207 out of range
  WARNING: drivers/net/phy/mdio_bus.c:76

Validate the PHY address before returning it from asix_read_phy_addr().

Reported-by: syzbot+3d43c9066a5b54902232@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=3d43c9066a5b54902232
Tested-by: syzbot+3d43c9066a5b54902232@syzkaller.appspotmail.com
Fixes: 7e88b11a862a ("net: usb: asix: refactor asix_read_phy_addr() and handle errors on return")
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
---
 drivers/net/usb/asix_common.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/usb/asix_common.c b/drivers/net/usb/asix_common.c
index 7fd763917ae2..6ab3486072cb 100644
--- a/drivers/net/usb/asix_common.c
+++ b/drivers/net/usb/asix_common.c
@@ -335,6 +335,11 @@ int asix_read_phy_addr(struct usbnet *dev, bool internal)
 	offset = (internal ? 1 : 0);
 	ret = buf[offset];
 
+	if (ret >= PHY_MAX_ADDR) {
+		netdev_err(dev->net, "invalid PHY address: %d\n", ret);
+		return -ENODEV;
+	}
+
 	netdev_dbg(dev->net, "%s PHY address 0x%x\n",
 		   internal ? "internal" : "external", ret);
 
-- 
2.43.0

Re: [PATCH] net: usb: asix: validate PHY address before use

Posted by Andrew Lunn 1 month, 3 weeks ago

On Wed, Dec 17, 2025 at 02:20:57PM +0530, Deepanshu Kartikey wrote:
> The ASIX driver reads the PHY address from the USB device via
> asix_read_phy_addr(). A malicious or faulty device can return an
> invalid address (>= PHY_MAX_ADDR), which causes a warning in
> mdiobus_get_phy():
> 
>   addr 207 out of range
>   WARNING: drivers/net/phy/mdio_bus.c:76
> 
> Validate the PHY address before returning it from asix_read_phy_addr().
> 
> Reported-by: syzbot+3d43c9066a5b54902232@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=3d43c9066a5b54902232
> Tested-by: syzbot+3d43c9066a5b54902232@syzkaller.appspotmail.com
> Fixes: 7e88b11a862a ("net: usb: asix: refactor asix_read_phy_addr() and handle errors on return")
> Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
> ---
>  drivers/net/usb/asix_common.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/net/usb/asix_common.c b/drivers/net/usb/asix_common.c
> index 7fd763917ae2..6ab3486072cb 100644
> --- a/drivers/net/usb/asix_common.c
> +++ b/drivers/net/usb/asix_common.c
> @@ -335,6 +335,11 @@ int asix_read_phy_addr(struct usbnet *dev, bool internal)
>  	offset = (internal ? 1 : 0);
>  	ret = buf[offset];
>  
> +	if (ret >= PHY_MAX_ADDR) {
> +		netdev_err(dev->net, "invalid PHY address: %d\n", ret);
> +		return -ENODEV;
> +	}
> +

https://elixir.bootlin.com/linux/v6.18.1/source/drivers/net/usb/ax88172a.c#L213

	ret = asix_read_phy_addr(dev, priv->use_embdphy);
	if (ret < 0)
		goto free;
	if (ret >= PHY_MAX_ADDR) {
		netdev_err(dev->net, "Invalid PHY address %#x\n", ret);
		ret = -ENODEV;
		goto free;
	}

Your change makes this a repeated netdev_err(). Please can you extend
your patch by removing this second error message.

    Andrew

---
pw-bot: cr