Linux Kernel Btrfs Denial-of-Service Vulnerability in Folio Mapping Handling

A denial-of-service vulnerability has been identified in the Linux kernel's Btrfs file system. The issue arises in the 'relocate_one_folio()' function, where the folio is unlocked after being read. This allows another thread to modify the folio's mapping before it is relocked, potentially leading to a null pointer dereference and a kernel crash. The vulnerability is particularly problematic when relocating data concurrently with transaction aborts, causing a crash by dereferencing a null pointer.

Impact

Exploitation of this vulnerability leads to a kernel crash due to a null pointer dereference, causing a denial-of-service condition.