GHSA-3HHF-GMJ4-Q58C
Vulnerability from github – Published: 2026-09-25 12:31 – Updated: 2026-09-25 12:31In the Linux kernel, the following vulnerability has been resolved:
bpf: Reject untrusted allocated-object pointers
When the final RCU read-side critical section ends, a local kptr is demoted to PTR_UNTRUSTED but retains MEM_ALLOC. The pointer may be NULL or may refer to an object whose lifetime is no longer protected.
type_is_ptr_alloc_obj() nevertheless recognizes any PTR_TO_BTF_ID with MEM_ALLOC as a live allocated object. In particular, a refcount-only local kptr never carries NON_OWN_REF, so it still passes the bpf_refcount_acquire() argument check after RCU protection ends. The kfunc can then dereference NULL or stale memory.
Make type_is_ptr_alloc_obj() reject PTR_UNTRUSTED pointers. Since type_is_non_owning_ref() is based on the same predicate, graph kfunc arguments obey the same live-object requirement. Fault-protected reads of the demoted pointer remain valid: writes are already rejected, and read fixups use bpf_may_fault_on_deref() rather than this predicate.
[ kkd: Rewrote commit log ]
{
"affected": [],
"aliases": [
"CVE-2026-98037"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-25T11:17:32Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject untrusted allocated-object pointers\n\nWhen the final RCU read-side critical section ends, a local kptr is demoted\nto PTR_UNTRUSTED but retains MEM_ALLOC. The pointer may be NULL or may refer\nto an object whose lifetime is no longer protected.\n\ntype_is_ptr_alloc_obj() nevertheless recognizes any PTR_TO_BTF_ID with\nMEM_ALLOC as a live allocated object. In particular, a refcount-only local\nkptr never carries NON_OWN_REF, so it still passes the\nbpf_refcount_acquire() argument check after RCU protection ends. The kfunc\ncan then dereference NULL or stale memory.\n\nMake type_is_ptr_alloc_obj() reject PTR_UNTRUSTED pointers. Since\ntype_is_non_owning_ref() is based on the same predicate, graph kfunc\narguments obey the same live-object requirement. Fault-protected reads of\nthe demoted pointer remain valid: writes are already rejected, and read\nfixups use bpf_may_fault_on_deref() rather than this predicate.\n\n[ kkd: Rewrote commit log ]",
"id": "GHSA-3hhf-gmj4-q58c",
"modified": "2026-09-25T12:31:34Z",
"published": "2026-09-25T12:31:34Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98037"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/092c2874dc1b2060fa77a465a971acd4fdf87683"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/135d542b97fa93e32c457d49d6e7b33ca7d05bae"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6b1f786ad85a0b63393b76f5e634deab1a73198c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7441ee8276641bddaf1cba7bb75ef9c1458ceb3b"
}
],
"schema_version": "1.4.0",
"severity": []
}
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