GHSA-6VJC-F3PW-3X6W
Vulnerability from github – Published: 2026-09-16 12:30 – Updated: 2026-09-16 12:30In 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.
{
"affected": [],
"aliases": [
"CVE-2026-89955"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-16T11:17:05Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/vfio-ap: Fix NULL deref in status_show() during queue probe\n\nWhen vfio_ap_mdev_probe_queue() creates the sysfs attribute group,\nthe queue\u0027s driver data has not yet been set. A concurrent read of\nthe \u0027status\u0027 attribute can therefore call dev_get_drvdata() and\nget NULL, which is then passed directly to\nvfio_ap_mdev_for_queue() where q-\u003eapqn is unconditionally\ndereferenced, causing a NULL pointer dereference.\n\nFix this by acquiring the update locks before calling\nsysfs_create_group(). The status_show() function acquires\nguests_lock before reading the driver data, so any concurrent\nread will block until after dev_set_drvdata() has been called\nand the update locks are released.\n\nAs a bonus, the APQN no longer needs to be read from the queue\nstruct after allocation \u2014 it can be read directly from apdev\nbefore allocation and stored in a local variable, which is then\nassigned to q-\u003eapqn once the allocation succeeds.",
"id": "GHSA-6vjc-f3pw-3x6w",
"modified": "2026-09-16T12:30:43Z",
"published": "2026-09-16T12:30:43Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89955"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/31fa0a8a3c337ed2d200166d6926ab23c14f8b2e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/69632952aca04caa71e49953b6949fc04e788e67"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7db2511fc601ca3a6e3fb1bdce02261c3c3167c3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dd6f4ef6f8a37412909ad787c837332fb070159c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e102ce0f4af99dff769a4b1b4daa4cc6bd5ad2d9"
}
],
"schema_version": "1.4.0",
"severity": []
}
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