A vulnerability in the Linux kernel’s btrfs subsystem causes a circular lock dependency during file operations. In btrfs_read_locked_inode(), btrfs_init_file_extent_tree() is called while a read‑locked path remains held, and the function can allocate memory that triggers kernel reclamation. The allocation attempts to acquire a mutex that is already implicitly owned through a dependency chain involving fs_reclaim, leading lockdep to report a circular lock dependency. If this scenario occurs in practice, it can result in a deadlock or kernel panic, effectively preventing file access and potentially disrupting the entire system.

The flaw affects the Linux kernel, specifically btrfs on kernel versions 6.17 and the 6.19 release candidates 1 through 8. Any system running these kernels with a btrfs mount and performing file open or sync operations is exposed; other filesystems or kernel versions not listed are not impacted.

The CVSS score of 5.5 indicates medium severity, while the EPSS score of less than 1% suggests a very low likelihood of exploitation. The vulnerability is not currently listed in CISA’s KEV catalog. Based on the description, it is inferred that the bug requires local access to a system mounting btrfs, as the lock contention occurs during standard file open or sync actions. An attacker with sufficient local privileges could induce the lock cycle and cause a kernel deadlock or crash, resulting in a denial of service for file operations or system‑wide impact.