crypto: algif_aead - Revert to operating out-of-place

A flaw in the Linux kernel's AEAD encryption interface allowed inefficient in-place memory operations that could be exploited. The fix reverts to safer out-of-place operations where input and output are kept separate, improving both security and performance.

CVE-2026-31431 addresses a vulnerability in the algif_aead (AEAD algorithm interface) within the Linux kernel's crypto subsystem where in-place encryption operations introduced unnecessary complexity and potential security risks. The vulnerability stems from attempting to operate on the same memory location for both source and destination when these buffers originate from different memory mappings; the remediation reverts to out-of-place operations that copy associated data directly, eliminating attack surface and improving reliability.