[PATCH 6.12 320/567] net: usb: asix: validate PHY address before use

Greg Kroah-Hartman
2026-01-06T17:33:43Z

From: Deepanshu Kartikey <kartikey406@gmail.com>

[ Upstream commit a1e077a3f76eea0dc671ed6792e7d543946227e8 ]

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 in asix_read_phy_addr() and remove the
now-redundant check in ax88172a.c.

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")
Link: https://lore.kernel.org/all/20251217085057.270704-1-kartikey406@gmail.com/T/ [v1]
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20251218011156.276824-1-kartikey406@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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);

--
2.51.0