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

Official 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 packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/1370badf6b823ce3cde39a65f46f9e5dc7b4bf43
• https://git.kernel.org/stable/c/ba6c4fc662853f6662e4db060cf88ee994053e21
• https://git.kernel.org/stable/c/9154542070ca7eadb3c764a882f39a127677854b
• https://git.kernel.org/stable/c/74f577c722c99248d804eca18e7de7c5e47549d7
• https://git.kernel.org/stable/c/0af37c217edf15fa21dac1c40822086df356c6bb