Linux Kernel Generic Netlink Callback Permission Bypass Vulnerability

A vulnerability in the Linux kernel's generic netlink implementation allows unauthorized callers to invoke bind callbacks, potentially leading to unintended behavior. This issue arises because the genl_bind function calls the bind callback before completing necessary permission checks, allowing callbacks to execute on behalf of unauthorized users while still reporting an error. The vulnerability affects the Linux kernel stable tree.

Impact

Exploitation of this vulnerability could result in unauthorized execution of bind callbacks, allowing malicious users to manipulate multicast group event handling on behalf of unauthorized callers.

Reproduction

To reproduce this vulnerability, create a generic netlink family with a bind callback that performs an action based on the presence of multicast group listeners. Then, attempt to bind to the group without the necessary permissions. The bind callback will be invoked despite the permission denial, allowing unauthorized manipulation of event handling.

Remediation

Users can upgrade to the latest version of the Linux kernel stable tree, where this vulnerability has been addressed. Instructions for downloading the patched version are available on the Linux kernel official website.