Executive brief
A vulnerability was identified in the Linux kernel's network filesystem library (netfslib) where data could be incorrectly handled during write operations. This issue occurs when a new write operation overlaps with existing unsaved data, potentially leading to data corruption or inconsistent file states. In a business context, this could affect the reliability of data stored on network-attached storage or distributed file systems, though it primarily impacts system stability and data integrity rather than direct security access.
Technical details
A vulnerability in netfs_perform_write() in the Linux kernel's netfslib was caused by improper handling of 'streaming writes' when they are overwritten. Specifically, when a folio (page cache unit) containing dirty data from a streaming write was entirely or partially overwritten by a subsequent write() call, the kernel failed to correctly discard or update the associated netfs_folio metadata. This could result in the folio being incorrectly marked as 'uptodate' or retaining stale dirty region tracking. The fix ensures that netfs_folio structures are properly freed or updated during overlapping write operations and correctly handles partial copy failures to maintain data integrity. The issue was identified using the fsx file system exerciser tool.
Affected products
- Linux Linux Kernel 8f52de0077ba to 7b4dcf1b9455
Timeline
- 2026-05-12: patched: Initial fix commit authored
- 2026-07-19: disclosed: CVE published