CVE-2026-97415: btrfs: tree-checker: validate names in ROOT_REF and ROOT_BACKREF

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-24 · updated 2026-10-03

Description

In the Linux kernel, the following vulnerability has been resolved: btrfs: tree-checker: validate names in ROOT_REF and ROOT_BACKREF ROOT_REF and ROOT_BACKREF items contain a struct btrfs_root_ref followed by the subvolume name. Several readers assume that this layout is already valid and then use the on-disk name length directly. A corrupted item can therefore make those readers address bytes outside the item, and BTRFS_IOC_GET_SUBVOL_INFO can copy too many bytes into its fixed-size UAPI name buffer. Validate ROOT_REF and ROOT_BACKREF items in tree-checker before any reader uses them. Reject records that do not contain a non-empty name, whose name_len does not exactly describe the remaining item payload, or whose name exceeds BTRFS_NAME_LEN. For BTRFS_IOC_GET_SUBVOL_INFO, copy only the validated on-disk name_len instead of deriving the copy length from the item size. The ioctl result is zeroed when allocated. That leaves the existing trailing zero byte untouched.

Affected products

Linux kernel: 4.18 — fixed in 7.2

How to fix

Upgrade to a fixed version: Linux kernel 7.2. Check the vendor advisory for mitigations.

References

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