CVE-2024-57839: 
Linux Kernel vulnerability analysis and mitigation

CVE-2024-57839 is a vulnerability in the Linux kernel's readahead functionality, discovered in January 2024. The issue stems from a problematic commit (7c877586da3) that attempted to properly shorten readahead when falling back to dopagecache_ra(). The vulnerability affects Linux kernels using NFS and can cause system hangs due to incorrect handling of readahead operations (Kernel Git).

The technical issue occurs when ra->size can be shrunk by readpages() call, which subsequently results in calling dopagecachera() with a negative number of pages (interpreted as a huge positive number). The vulnerability was identified in the readahead code specifically when used with NFS. The problematic code was located in mm/readahead.c and involved calculations related to page cache readahead operations (Kernel Git).

The primary impact of this vulnerability is system stability issues, specifically causing occasional hangs when the affected kernels are used with NFS. Additionally, the implemented fix results in reduced readahead throughput due to readahead window confusion, though this is considered preferable to system hangs (NVD).

The issue has been addressed by reverting commit 7c877586da3 as a temporary solution until a proper fix can be developed. The fix has been implemented in various Linux distributions including Debian's bullseye (5.10.234-1), bookworm (6.1.128-1), and sid/trixie (6.12.17-1) releases (Debian Tracker).