Linux Kernel NULL Pointer Dereference Vulnerability in Filemap Handling

A vulnerability in the Linux kernel's filemap component can lead to a NULL pointer dereference. This issue arises when a read operation races with an invalidation, followed by another read, allowing a folio to be replaced with a higher-order folio. Consequently, a sibling entry for the new folio may appear in the next iteration of the processing loop, causing the NULL pointer dereference while holding the RCU read lock. The vulnerability has been addressed by modifying the read handling to correctly process the new folio in such race conditions.

Impact

Exploitation of this vulnerability leads to a NULL pointer dereference, causing a crash or denial-of-service condition on the affected system.