GHSA-6JX2-QMXH-94V4
Vulnerability from github – Published: 2026-09-17 18:32 – Updated: 2026-09-18 18:31In the Linux kernel, the following vulnerability has been resolved:
bpf: Invalidate RCU pointers after final spin unlock
In a sleepable BPF program, a spin lock can provide the only RCU protection for a kptr. The final bpf_spin_unlock() ends that protection, but the verifier leaves the pointer valid. Another CPU can then free the object before the pointer is used. A capability-limited runtime PoC triggered a task_struct use-after-free in __bpf_get_task_stack().
Record whether the program is in an RCU-protected context before releasing the lock. Invalidate RCU-protected pointers only when the unlock leaves the final such context. This preserves valid pointers in non-sleepable programs and inside an explicit RCU read-side section.
{
"affected": [],
"aliases": [
"CVE-2026-90317"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-17T17:17:29Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Invalidate RCU pointers after final spin unlock\n\nIn a sleepable BPF program, a spin lock can provide the only RCU protection\nfor a kptr. The final bpf_spin_unlock() ends that protection, but the\nverifier leaves the pointer valid. Another CPU can then free the object\nbefore the pointer is used. A capability-limited runtime PoC triggered a\ntask_struct use-after-free in __bpf_get_task_stack().\n\nRecord whether the program is in an RCU-protected context before releasing\nthe lock. Invalidate RCU-protected pointers only when the unlock leaves the\nfinal such context. This preserves valid pointers in non-sleepable programs\nand inside an explicit RCU read-side section.",
"id": "GHSA-6jx2-qmxh-94v4",
"modified": "2026-09-18T18:31:29Z",
"published": "2026-09-17T18:32:00Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90317"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/180c7000712db77063b3a26f4c97e7dd9038f449"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7ae71629357d0a6d0bdadb929c7b296d5b7e61c2"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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