nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke
Published Sep 11, 2026
9.8
CRITICALCVSS 3.1
EPSS 0.66%
Description
nfsd4_alloc_layout_stateid reads fp->fi_deleg_file without holding fi_lock when the parent stateid is a delegation. A concurrent delegation revoke via the laundromat can clear fi_deleg_file under fi_lock, causing nfsd_file_get() to return NULL and triggering the BUG_ON.
This race is client-reachable: two NFS clients can trigger it by having one hold a delegation while another opens the same file to force a recall. When the first client doesn't respond to the recall, the laundromat revokes it. A concurrent LAYOUTGET from any client using the delegation stateid hits the race window.
Fix this by taking fi_lock around the fi_deleg_file read in the SC_TYPE_DELEG path, matching the locking discipline of the find_any_file() arm, and replacing the BUG_ON with a graceful error return that cleans up the partially-initialized layout stateid.
Affected products
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- Version StatusaffectedConstraints
- Version StatusaffectedConstraints
- Version StatusaffectedConstraints
- Version StatusaffectedConstraints
- Version
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- Version 4.0StatusaffectedConstraints-
- Version 0StatusunaffectedConstraints<4.0
- Version 6.12.109StatusunaffectedConstraints<=6.12.*
- Version 6.18.50StatusunaffectedConstraints<=6.18.*
- Version 7.2.4StatusunaffectedConstraints<=7.2.*
- Version 7.3-rc1StatusunaffectedConstraints<=*
- Version
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
No data.
No data.
Red Hat Enterprise Linux 10
kernel
Affected
Red Hat Enterprise Linux 10
kernel-rt
Affected
Red Hat Enterprise Linux 6
kernel
Not affected
Red Hat Enterprise Linux 7
kernel
Affected
Red Hat Enterprise Linux 7
kernel-rt
Affected
Red Hat Enterprise Linux 8
kernel
Affected
Red Hat Enterprise Linux 8
kernel-rt
Affected
Red Hat Enterprise Linux 9
kernel
Affected
Red Hat Enterprise Linux 9
kernel-rt
Affected
Red Hat OpenShift Container Platform 4
openshift/ose-rhel-coreos-8
Affected
Red Hat OpenShift Container Platform 4
openshift/ose-rhel-coreos-9
Affected
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Affected | n/a |
| Red Hat Enterprise Linux 10 | kernel-rt | Affected | n/a |
| Red Hat Enterprise Linux 6 | kernel | Not affected | n/a |
| Red Hat Enterprise Linux 7 | kernel | Affected | n/a |
| Red Hat Enterprise Linux 7 | kernel-rt | Affected | n/a |
| Red Hat Enterprise Linux 8 | kernel | Affected | n/a |
| Red Hat Enterprise Linux 8 | kernel-rt | Affected | n/a |
| Red Hat Enterprise Linux 9 | kernel | Affected | n/a |
| Red Hat Enterprise Linux 9 | kernel-rt | Affected | n/a |
| Red Hat OpenShift Container Platform 4 | openshift/ose-rhel-coreos-8 | Affected | n/a |
| Red Hat OpenShift Container Platform 4 | openshift/ose-rhel-coreos-9 | Affected | n/a |
No package ranges for this CVE.
Remediation
No remediation recorded yet.
References (9)
- https://access.redhat.com/security/cve/CVE-2026-89686 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2532098 Issue Tracking
- https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89686.mbox
- https://git.kernel.org/stable/c/607a56fea772c1f4f4989d8e255dd4f7192d9604
- https://git.kernel.org/stable/c/97bda8b4284d90897a1f1922e5082ff9e35d7c7e
- https://git.kernel.org/stable/c/c517f27498757e616d2a8fe6d16caad1fee422e6
- https://git.kernel.org/stable/c/ca94ba36172046be6a694a7986f6931e47ed4d51
- https://nvd.nist.gov/vuln/detail/CVE-2026-89686
- https://www.cve.org/CVERecord?id=CVE-2026-89686
Change history (0)
No recorded changes yet.