Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2026-89958— s390/vfio-ap: Fix dereference matrix_mdev->kvm without checking for NULL

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Linux 内核中，以下漏洞已得到修复： s390/vfio-ap：修复在未检查 是否为 NULL 的情况下对其进行解引用的问题 结构体中包含两个指向回调函数的函数指针字段： ：在 AP 总线扫描函数开始时被调用，用于通知设备驱动程序宿主机的 AP 配置已发生变更，相关的 AP 设备将相应地被添加或删除。这为实施者提供了一次机会，以便在相关设备被添加或删除之前评估配置变更并作出响应。 ：在 AP 总线扫描函数结束时被调用，用于通知设备驱动程序宿主机的 AP 配置已发生变更，且 AP 设备已相应地被添加或删除。这

AI Predicted 5.5 Difficulty: Moderate EPSS 0.21% · P10

Affected Version Matrix 12

VendorProduct Version RangeStatus
Linux Linux eeb386aeb5b7c8d2dae6a3ba49255d8a97803182< 5e932abfcce6189d067fffb0eb8214443bc04374 affected
eeb386aeb5b7c8d2dae6a3ba49255d8a97803182< 334b435b951353f934d5110c4630e0cb58d2f9a7 affected
eeb386aeb5b7c8d2dae6a3ba49255d8a97803182< 178ea7a1c2c3c0c01d14b8f60aa35f1e0cdc6b78 affected
eeb386aeb5b7c8d2dae6a3ba49255d8a97803182< 4f7e869d0db24ae07b4c888fd3bc21554eef775d affected
eeb386aeb5b7c8d2dae6a3ba49255d8a97803182< d50346801b4f144e42b49cd4f1496010498ab114 affected
6.0 affected
< 6.0 unaffected
6.6.157≤ 6.6.* unaffected
… +4 more rows
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-89958

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
s390/vfio-ap: Fix dereference matrix_mdev->kvm without checking for NULL
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: s390/vfio-ap: Fix dereference matrix_mdev->kvm without checking for NULL The ap_driver structure has two fields which are function pointers to callbacks: * .on_config_changed: called at the start of the AP bus scan function to notify the device driver that the host AP configuration has changed and the associated AP devices will be added or removed accordingly. This gives the implementor a chance to evaluate the configuration changes and respond to them before the associated devices are added or removed. * .on_scan_complete: Called at the end of the AP bus scan function to notify the device driver that the host AP configuration has changed and the AP devices have been added or removed accordingly. This gives the implementor the opportunity to respond to the changes after the associated devices are added or removed. These two callbacks are implemented in the vfio_ap device driver via the vfio_ap_on_cfg_changed and vfio_ap_on_scan_complete functions respectively. Within the call stack of these two callback functions the matrix_mdev->kvm->lock mutex is taken without checking whether matrix_mdev->kvm is NULL or not. If matrix_mdev->kvm has never been set, trying to take the lock will trigger a NULL pointer dereference. This patch adds checks for matrix_mdev->kvm == NULL before taking the matrix_mdev->kvm->lock mutex. Note that the matrix_mdev->kvm->lock mutex taken in the vfio_ap_mdev_hot_plug_config function is moved to the calling function along with the matrix_dev->mdevs_lock which is needed there to access the fields of the matrix_mdev. It makes little sense to make the change the check for matrix_mdev->kvm there before taking the kvm->lock mutex only to have to move it out via another patch, so it is done in this patch. It is important to make note of the following: 1. The matrix_dev->guests_lock is acquired at the start of both callback functions. This ensures that matrix_mdev will not be removed via the vfio_ap_mdev_remove function because it too takes matrix_dev_guests_lock before removing the object; so, matrix_mdev will be available for the duration of the callback functions. 2. The matrix_dev->mdevs_lock mutex must be taken in order to access fields within the matrix_mdev structure 3. matrix_mdev->kvm->lock mutex must be taken before the matrix_dev->mdevs_lock to prevent a lockdep splat. 4: The kvm->lock must be held while plugging the guest's AP configuration into its SIE state description via the vfio_ap_mdev_update_guest_apcb function. 5. The vfio_ap_mdev_update_guest_apcb checks matrix_mdev->kvm to verify it is not NULL before doing the hot plug of the guest's AP configuration.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux eeb386aeb5b7c8d2dae6a3ba49255d8a97803182 ~ 5e932abfcce6189d067fffb0eb8214443bc04374 -
Linux Linux 6.0 -

II. Public POCs for CVE-2026-89958

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-89958

请登录查看更多情报信息。

Other References for CVE-2026-89958 (5)

Same Patch Batch · Linux · 2026-09-16 · 276 CVEs total

CVE-2026-90048 9.8 CRITICAL fs/ntfs3: fix slab-out-of-bounds write in ni_create_attr_list()
CVE-2026-90012 9.8 CRITICAL spi: Fix DMA mapping ownership on partial map failure
CVE-2026-89970 9.8 CRITICAL nvmet-auth: Synchronize timeout work during SQ teardown
CVE-2026-89857 9.8 CRITICAL scsi: qla2xxx: Hold qpair lock when sending NVMe LS reject
CVE-2026-89969 9.8 CRITICAL nvmet-tcp: fix out-of-bounds write when receiving an over-long PDU
CVE-2026-89847 9.8 CRITICAL scsi: qla2xxx: Avoid double completion in async IOCB timeout
CVE-2026-89972 9.8 CRITICAL nvme: add missing SRCU grace period in error path
CVE-2026-89990 9.8 CRITICAL ceph: lock mutex in ceph_mds_check_access()
CVE-2026-90036 9.8 CRITICAL NFSD: Prevent client use-after-free during blocked-lock reaping
CVE-2026-90038 9.8 CRITICAL NFSD: Prevent client use-after-free during export state revocation
CVE-2026-90037 9.8 CRITICAL NFSD: Prevent client use-after-free during close_lru reaping
CVE-2026-89788 9.8 CRITICAL ksmbd: fix tree connection use-after-free in smb2_tree_connect()
CVE-2026-89783 9.8 CRITICAL xfrm6: fix out-of-bounds write in xfrm6_input_addr() when secpath is full
CVE-2026-90042 9.8 CRITICAL ceph: properly decrypt filenames in vmalloc() buffers
CVE-2026-89778 9.8 CRITICAL isofs: fix out-of-bounds page array access on empty zisofs block
CVE-2026-89915 9.3 CRITICAL KVM: arm64: Remove VM-wide VNCR mapping counter
CVE-2026-90049 9.3 CRITICAL net: skbuff: don't skb_tx_error() the source skb in skb_zerocopy()
CVE-2026-89775 9.3 CRITICAL KVM: arm64: Handle negative S1 walk levels in VNCR TLB size evaluation
CVE-2026-89916 9.3 CRITICAL KVM: arm64: Make VNCR invalidation participate in MMU invalidation retry
CVE-2026-89930 9.3 CRITICAL KVM: nVMX: Service local TLB flushes on failed nested VM-Enter

Showing top 20 of 276 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-89958

No comments yet

Leave a comment