sunrpc: defer rq_argp and rq_resp free until after RCU grace period
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 4 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
Summary
In the Linux kernel, the following vulnerability has been resolved: sunrpc: defer rq_argp and rq_resp free until after RCU grace period svc_rqst_free() frees rqstp->rq_argp and rqstp->rq_resp synchronously via kfree(), but defers the rqstp struct free via kfree_rcu(). After svc_exit_thread() calls list_del_rcu() and svc_rqst_free(), there is a window where RCU readers that started before list_del_rcu() can still traverse the thread list and find the rqstp. These readers (e.g. nfsd_nl_rpc_status_get_dumpit()) dereference rqstp->rq_argp, which has already been freed — a use-after-free. Fix this by moving the kfree of rq_argp and rq_resp into an explicit call_rcu() callback alongside the struct free. Resources not accessed by RCU readers (bvec, buffer pages, scratch folio, auth_data) remain synchronously freed.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.1.191, 6.12.111, 6.18.50, 7.2.4, 7.3
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet |
| Red Hat Enterprise Linux 7 | Affected | No fix yet |
| Red Hat Enterprise Linux 8 | Affected | No fix yet |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
Not affected: 1 product
- Red Hat Enterprise Linux 6
Timeline
- 2026-10-02 Threatist record created from CVE-2026-89545
- 2026-10-03 Alias added: GHSA-43p7-fx92-rp4x
- 2026-10-18 CISA SSVC decision points changed
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-30 Affected versions changed · Red Hat
- 2026-10-30 Fix available: Linux/[email protected], Linux/Linux@c977158237bccc3d2512d5b17c47ee3760dc8839 · CNA
- 2026-10-30 1 new reference · CNA
- 2026-11-01 Affected versions changed · Red Hat
- 2026-11-01 CVSS score changed · Red Hat
References
Other 5
- https://git.kernel.org/stable/c/c977158237bccc3d2512d5b17c47ee3760dc8839
- https://git.kernel.org/stable/c/0ea49d69aa806008b2424c8cf21cf746b9963967
- https://git.kernel.org/stable/c/08bc49e0541260bf294962cf889a32a2d2713ad6
- https://git.kernel.org/stable/c/e0c5693d3f9a5d4911735ab0e0eba4eecb1f1090
- https://git.kernel.org/stable/c/c479bde671cbe2f9e152834a8b0eb7c3c295bbaf
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Sources
- CVE-2026-89545 · CVE Program
- CVE-2026-89545 · NVD
- FIRST EPSS
- GHSA-43p7-fx92-rp4x · GitHub Advisory Database · CC BY 4.0
- CVE-2026-89545 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences