Executive brief
A vulnerability was identified in the Linux kernel's network filesystem (netfs) component, which manages how data is written to network-based storage. Under specific conditions, the system fails to correctly track internal data structures during write operations, leading to memory leaks. While primarily a stability and performance issue, persistent leaks can eventually exhaust system resources, potentially causing system slowdowns or crashes.
Technical details
A vulnerability in netfs_perform_write() in the Linux kernel's netfs subsystem arises from incorrect handling of folio->private data. The function fails to properly transition folio->private between NULL, NETFS_FOLIO_COPY_TO_CACHE, and netfs_folio/netfs_group structures. This mismanagement leads to multiple attachments of private data to a single folio, resulting in reference count leaks for folios and leaks of netfs_folio and netfs_group structures. An attacker or a series of specific I/O operations could trigger these leaks, leading to kernel memory exhaustion. The fix consolidates the 'uptodate' marking logic and ensures proper cleanup of existing private data before attaching new groups.
Affected products
- Linux Linux Kernel 6.12, 6.18.34, 7.0.11
Timeline
- 2026-07-19: disclosed
- 2026-07-19: advisory