Linux Kernel Memory Cgroup NULL Pointer Dereference Vulnerability

A vulnerability in the Linux kernel's memory cgroup (memcg) implementation can lead to a NULL pointer dereference. This issue arises when the kernel's hwpoison feature forcibly uncharges a least recently used (LRU) hwpoisoned page. In such cases, the associated memory cgroup can be NULL, causing the 'mem_cgroup_track_foreign_dirty_slowpath()' function to dereference a NULL pointer. The vulnerability has been addressed by ensuring that foreign writebacks are not recorded for folios with a NULL memory cgroup.

Impact

Exploitation of this vulnerability leads to a NULL pointer dereference, causing a kernel crash.