CVE-2024-26996

/// Technical description

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

usb: gadget: f_ncm: Fix UAF ncm object at re-bind after usb ep transport error

When ncm function is working and then stop usb0 interface for link down,

eth_stop() is called. At this piont, accidentally if usb transport error

should happen in usb_ep_enable(), 'in_ep' and/or 'out_ep' may not be enabled.

After that, ncm_disable() is called to disable for ncm unbind

but gether_disconnect() is never called since 'in_ep' is not enabled.

As the result, ncm object is released in ncm unbind

but 'dev->port_usb' associated to 'ncm->port' is not NULL.

And when ncm bind again to recover netdev, ncm object is reallocated

but usb0 interface is already associated to previous released ncm object.

Therefore, once usb0 interface is up and eth_start_xmit() is called,

released ncm object is dereferrenced and it might cause use-after-free memory.

[function unlink via configfs]

usb0: eth_stop dev->port_usb=ffffff9b179c3200

--> err

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References