Linux Kernel Zswap Resource Management Vulnerability During CPU Hot Unplug

A use-after-free vulnerability has been identified in the Linux kernel's zswap feature, specifically in the compression and decompression functions. This issue arises because the per-CPU context for asynchronous compression operations is not properly synchronized during CPU hot unplug events. When a CPU is hot unplugged, resources associated with the compression context can be freed while still in use, leading to a use-after-free condition. This vulnerability was introduced when zswap switched to the crypto_acomp API for hardware acceleration, allowing operations to migrate between CPUs without proper synchronization. The vulnerability affects several versions of the Linux kernel.

Impact

Exploitation of this vulnerability can lead to a use-after-free condition, potentially allowing for arbitrary memory access or manipulation.

Remediation

The vulnerability has been addressed in the Linux kernel by synchronizing resource management during CPU hot unplug events. Users should upgrade to the latest stable version of the Linux kernel where this vulnerability has been fixed.