CVE-2026-89645

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

btrfs: drop recovered reloc root refs on recovery failure

During relocation recovery, each fs root gets a reference to its relocation

root. If loading or adding a later root fails, or if the first transaction

commit fails, btrfs_recover_relocation() jumps to out_unset before

merge_reloc_roots() and clean_dirty_subvols().

put_reloc_control() drops the list-owned relocation root references, but it

does not clear fs_root->reloc_root or drop the references owned by those

pointers. Mount cleanup only drops them when BTRFS_FS_ERROR is set, so an

error such as -ENOMEM while processing a later root can leave references

behind.

Keep temporary references to the fs roots associated during recovery. On

failure, clear their reloc_root pointers and drop the corresponding

references. Once the first transaction commit succeeds, drop only the

temporary fs root references and let the normal merge and cleanup paths

handle the relocat

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References