CVE-2026-89955
In the Linux kernel, the following vulnerability has been resolved: s390/vfio-ap: Fix NULL deref in status_show() during queue probe When vfio_ap_mdev_probe_queue() creates the sysfs attribute group, the queue's driver data has not yet been set. A concurrent read of the 'status' attribute can therefore call dev_get_drvdata() and get NULL, which is then passed directly to vfio_ap_mdev_for_queue() where q->apqn is unconditionally dereferenced, causing a NULL pointer dereference. Fix this by acquiring the update locks before calling sysfs_create_group(). The status_show() function acquires guests_lock before reading the driver data, so any concurrent read will block until after dev_set_drvdata() has been called and the update locks are released. As a bonus, the APQN no longer needs to be read from the queue struct after allocation — it can be read directly from apdev before allocation and stored in a local variable, which is then assigned to q->apqn once the allocation succeeds.
Executive briefing
The source record describes: In the Linux kernel, the following vulnerability has been resolved: s390/vfio-ap: Fix NULL deref in status_show() during queue probe When vfio_ap_mdev_probe_queue() creates the sysfs attribute group, the queue's driver data has not yet been set. A concurrent read of the 'status' attribute can therefore call dev_get_drvdata() and get NULL, which is then passed directly to vfio_ap_mdev_for_queue() where q->apqn is unconditionally dereferenced, causing a NULL pointer dereference. Fix this by acquiring the update locks before calling sysfs_create_group(). The status_show() function acquires guests_lock before reading the driver data, so any concurrent read will block until after dev_set_drvdata() has been called and the update locks are released. As a bonus, the APQN no longer needs to be read from the queue struct after allocation — it can be read directly from apdev before allocation and stored in a local variable, which is then assigned to q->apqn once the allocation succeeds. The practical risk depends on whether an affected product/version is present, reachable and configured in an exploitable way. Review the affected-product evidence and linked vendor advisories before assigning exposure status.
Evidence confidence: Low Evidence-derived, not an exploitability verdict
Severity & attack characteristics
CVSS vector:
No CVSS vector is currently available in the source record.
Technical explanation & impact
The technical mechanism is not expanded beyond the source description unless a referenced advisory supplies additional evidence. Read the linked vendor/CERT advisories for root-cause detail.
Potential impact must be interpreted from the published CVSS impact metrics and the affected component. A CVSS impact score is not proof that a particular asset is exploitable.
Affected products and versions
NVD has not supplied machine-readable vulnerable CPE product/version entries for this CVE. This is an information gap, not proof that no products are affected. Check the vendor advisory references below.
Remediation & validation
- Identify exposure by comparing the affected product and version ranges with your asset inventory, SBOM and externally exposed services.
- Review the linked vendor security advisory or patch notes. Upgrade to a vendor-confirmed fixed release; do not infer a fixed version from the CVE description.
- Until patched, consider restricting network access or disabling the affected feature where operationally safe. These are temporary controls, not a substitute for a vendor fix.
- Validate the remediation with a version check and vulnerability rescan, then retain change evidence.
No fixed version is displayed unless it is explicitly established by a vendor advisory. Follow the vendor's release notes for exact product and branch applicability.
Vendor advisories, patches & exploit references
- https://git.kernel.org/stable/c/10606c9af18baed75cd180b96ee695441aa15134 REFERENCE 416baaa9-dc9f-4396-8d5f-8c081fb06d67
- https://git.kernel.org/stable/c/31fa0a8a3c337ed2d200166d6926ab23c14f8b2e REFERENCE 416baaa9-dc9f-4396-8d5f-8c081fb06d67
- https://git.kernel.org/stable/c/69632952aca04caa71e49953b6949fc04e788e67 REFERENCE 416baaa9-dc9f-4396-8d5f-8c081fb06d67
- https://git.kernel.org/stable/c/7db2511fc601ca3a6e3fb1bdce02261c3c3167c3 REFERENCE 416baaa9-dc9f-4396-8d5f-8c081fb06d67
- https://git.kernel.org/stable/c/dd6f4ef6f8a37412909ad787c837332fb070159c REFERENCE 416baaa9-dc9f-4396-8d5f-8c081fb06d67
- https://git.kernel.org/stable/c/e102ce0f4af99dff769a4b1b4daa4cc6bd5ad2d9 REFERENCE 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Information gaps & confidence notes
These gaps indicate missing source data. CVE Watch does not fill them with guessed product, exploit or patch details.
- NVD does not currently provide machine-readable vulnerable CPE product/version entries for this record.
- No vendor advisory or patch reference was identified in the supplied CVE references.
- No CVSS vector is currently available in the source record.
- No CWE classification is currently available.
Last enrichment: 2026-11-09T13:17:57+00:00 · Source last modified: 2026-10-30T13:20:36.663