CVE-2026-98047

/// Technical description

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

bpf: Check ancestor frames for rbtree callbacks

bpf_rbtree_add() invokes its comparator while the caller holds the root

lock. The native insertion code retains raw parent and link pointers across

the callback, so the verifier prohibits unlocking, consuming tree nodes,

or changing RCU state from that callback.

in_rbtree_lock_required_cb() only checks the innermost verifier frame.

Static subprogram calls are permitted while holding a spin lock, and such a

call pushes a frame without in_callback_fn set. Consequently, all callback

restrictions disappear in the nested frame. The subprogram can unlock the

tree, remove and drop the node being compared, then relock. Native insertion

resumes with the stale parent pointer and links freed memory into the tree.

Walk all active frames for the rbtree callback instead. Benign static

subprograms remain permitted, while callback restrictions follow execution

into nested frames.

/// 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