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.
Published: 2026-09-25
Score: n/a
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

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History

Fri, 25 Sep 2026 17:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-416

Fri, 25 Sep 2026 10:30:00 +0000

Type Values Removed Values Added
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.
Title bpf: Check ancestor frames for rbtree callbacks
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-09-25T10:23:57.347Z

Reserved: 2026-09-25T10:19:56.072Z

Link: CVE-2026-98047

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-25T11:17:33.553

Modified: 2026-09-25T11:17:33.553

Link: CVE-2026-98047

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-25T17:15:15Z

Weaknesses