What happened
In the Linux kernel, the following vulnerability has been resolved: btrfs: fix reloc root cleanup in merge_reloc_roots() If the root we got has zero root refs in its root item, we are resetting the root's ->reloc_root without using barriers like we do everywhere else. Sashiko complained about this while reviewing another patch, and it's correct (see the Link tag below). Also, we should not clear BTRFS_ROOT_DEAD_RELOC_TREE from the root unless the root points to the reloc root we have. Fix this by using clear_reloc_root(), which issues the memory barrier after setting the root's ->reloc_root to NULL and before clearing the bit BTRFS_ROOT_DEAD_RELOC_TREE from the root.
Affected versions
Linux: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 through before ab48583aa9948205ff9a6470e23dbff74c565e24 (git); 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 through before 63d6b1f04cd91c825329712aa526215ffa5d11ca (git); 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 through before b78fe9563e2d5ae47805f1e5dc722c91fd30e1f8 (git); before 6.12.111 (semver); before 6.18.53 (semver) Fixed: See vendor advisory.
Why it matters
Review the vendor advisory and exposure of the affected product to determine operational impact.
Detection & mitigation
- Apply vendor-provided updates or mitigations.
- Review affected product exposure and access logs.
Public PoC references
No public PoC reference has passed the current publication threshold.