CVE-2021-47072

/// Technical description

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

btrfs: fix removed dentries still existing after log is synced

When we move one inode from one directory to another and both the inode

and its previous parent directory were logged before, we are not supposed

to have the dentry for the old parent if we have a power failure after the

log is synced. Only the new dentry is supposed to exist.

Generally this works correctly, however there is a scenario where this is

not currently working, because the old parent of the file/directory that

was moved is not authoritative for a range that includes the dir index and

dir item keys of the old dentry. This case is better explained with the

following example and reproducer:

# The test requires a very specific layout of keys and items in the

# fs/subvolume btree to trigger the bug. So we want to make sure that

# on whatever platform we are, we have the same leaf/node size.

#

# Currently in btrfs the node/leaf size can n

/// 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