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([2405:201:682f:389d:a45b:c390:af5a:2503]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7fe70c4b853sm106470b3a.45.2025.12.17.17.12.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Dec 2025 17:12:05 -0800 (PST) From: Deepanshu Kartikey To: andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, khalasa@piap.pl, andriy.shevchenko@linux.intel.com Cc: o.rempel@pengutronix.de, linux-usb@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Deepanshu Kartikey , syzbot+3d43c9066a5b54902232@syzkaller.appspotmail.com Subject: [PATCH v2] net: usb: asix: validate PHY address before use Date: Thu, 18 Dec 2025 06:41:56 +0530 Message-ID: <20251218011156.276824-1-kartikey406@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 (>=3D 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=3D3d43c9066a5b54902232 Tested-by: syzbot+3d43c9066a5b54902232@syzkaller.appspotmail.com Fixes: 7e88b11a862a ("net: usb: asix: refactor asix_read_phy_addr() and han= dle errors on return") Link: https://lore.kernel.org/all/20251217085057.270704-1-kartikey406@gmail= .com/T/ [v1] Signed-off-by: Deepanshu Kartikey Reviewed-by: Andrew Lunn --- v2: - Remove redundant validation check in ax88172a.c (Andrew Lunn) --- drivers/net/usb/asix_common.c | 5 +++++ drivers/net/usb/ax88172a.c | 6 +----- 2 files changed, 6 insertions(+), 5 deletions(-) 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 intern= al) offset =3D (internal ? 1 : 0); ret =3D buf[offset]; =20 + if (ret >=3D 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); =20 diff --git a/drivers/net/usb/ax88172a.c b/drivers/net/usb/ax88172a.c index f613e4bc68c8..758a423a459b 100644 --- a/drivers/net/usb/ax88172a.c +++ b/drivers/net/usb/ax88172a.c @@ -210,11 +210,7 @@ static int ax88172a_bind(struct usbnet *dev, struct us= b_interface *intf) ret =3D asix_read_phy_addr(dev, priv->use_embdphy); if (ret < 0) goto free; - if (ret >=3D PHY_MAX_ADDR) { - netdev_err(dev->net, "Invalid PHY address %#x\n", ret); - ret =3D -ENODEV; - goto free; - } + priv->phy_addr =3D ret; =20 ax88172a_reset_phy(dev, priv->use_embdphy); --=20 2.43.0