Linux Kernel Poly1305 Register Corruption Vulnerability in No-SIMD Contexts

A vulnerability in the Linux kernel's Poly1305 implementation for ARM64 architecture has been addressed. The issue involved register corruption when Poly1305 functions were called in contexts where SIMD registers were unavailable. This vulnerability arose because the necessary check for SIMD usability had been removed in a previous commit. The Poly1305 functions are not meant to be used when SIMD registers cannot be utilized, but if they are called under such conditions, they should handle the situation correctly instead of damaging the registers of other tasks or producing incorrect Message Authentication Codes (MACs). The fix also ensures that the Poly1305 unit test can pass.

Impact

The vulnerability could lead to unintended register corruption in the context of the calling task, potentially disrupting the execution of other tasks and causing incorrect computations in applications that rely on the Poly1305 MAC function.

Remediation

Users can apply the latest patches available in the Linux kernel stable tree to address this vulnerability.