net: ch9200: fix uninitialised access during mii_nway_restart
CVE: CVE-2025-38086
Component: kernel
CWE: CWE-908
Severity: Moderate
CVSS v3: 7.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Release date: 2025-06-28T00:00:00+00:00

In the Linux kernel, the following vulnerability has been resolved:

net: ch9200: fix uninitialised access during mii_nway_restart

In mii_nway_restart() the code attempts to call
mii->mdio_read which is ch9200_mdio_read(). ch9200_mdio_read()
utilises a local buffer called "buff", which is initialised
with control_read(). However "buff" is conditionally
initialised inside control_read():

        if (err == size) {
                memcpy(data, buf, size);
        }

If the condition of "err == size" is not met, then
"buff" remains uninitialised. Once this happens the
uninitialised "buff" is accessed and returned during
ch9200_mdio_read():

        return (buff[0] | buff[1] << 8);

The problem stems from the fact that ch9200_mdio_read()
ignores the return value of control_read(), leading to
uinit-access of "buff".

To fix this we should check the return value of
control_read() and return early on error.


Remediation:
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.