SB20260928160 - Untrusted Pointer Dereference in Linux kernel BPF verifier type_is_ptr_alloc_obj() predicate

Description

This security bulletin contains information about 1 vulnerability.

1) Untrusted Pointer Dereference (CVE-ID: CVE-2026-98037)

CWE-ID: CWE-822 - Untrusted Pointer Dereference

CVSSv4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

The vulnerability allows a local user to trigger a NULL or stale-memory dereference.

The vulnerability exists due to improper validation of untrusted pointer state in the BPF verifier's type_is_ptr_alloc_obj() predicate when validating a refcount-only local kptr after RCU protection ends. A local user can pass a demoted local kptr to bpf_refcount_acquire() to trigger a NULL or stale-memory dereference.

Fault-protected reads of the demoted pointer remain valid.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/092c2874dc1b2060fa77a465a971acd4fdf87683
• https://git.kernel.org/stable/c/135d542b97fa93e32c457d49d6e7b33ca7d05bae
• https://git.kernel.org/stable/c/6b1f786ad85a0b63393b76f5e634deab1a73198c
• https://git.kernel.org/stable/c/7441ee8276641bddaf1cba7bb75ef9c1458ceb3b