Linux Kernel Userspace-Supplied xdp_desc Validation Vulnerability in XSK

A vulnerability has been identified in the Linux kernel's handling of user-supplied xdp_desc values in the XSK (eXpress Data Path) subsystem. This issue arises because certain clearly invalid descriptors can bypass the alignment validation functions, leading to undefined behavior or the queuing of invalid frames for transmission. Specifically, descriptors with lengths near 'U32_MAX' and non-zero metadata lengths can cause positive integer overflow, while low addresses with non-zero metadata lengths can result in negative integer overflow. Both scenarios can exploit the validation process, although this vulnerability does not affect legitimate XSK applications.

Impact

Exploitation of this vulnerability can lead to undefined behavior or the transmission of invalid frames, potentially causing disruptions in network communication or application performance.

Reproduction

To reproduce this vulnerability, create a user-space application that interacts with the XSK subsystem and deliberately sends xdp_desc values that are clearly invalid, such as those that exploit the described integer overflow scenarios. The invalid descriptors can bypass the validation checks and lead to undefined behavior or the queuing of invalid frames for transmission.

Remediation

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