CVE-2026-89960— s390/vfio-ap: fix stale pqap_hook pointer on error in vfio_ap_mdev_set_kvm()
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，已修复以下漏洞： s390/vfio-ap：修复 vfio_ap_mdev_set_kvm() 中错误路径下 pqap_hook 指针未更新的问题 在 函数中， 被提前设置为 ，此时尚未获取更新锁（update locks），也未检查 mdev 列表是否存在冲突的分配。如果另一个 mdev 已经绑定到同一个 KVM 实例，该函数将返回 错误，但不会恢复（restore）原来的 hook 指针。这导致 指向了失败的 ，而不是合法拥有该 KVM 实例的那个 mdev。 由于在此错误路径中， 从未
Possible ATT&CK Techniques 3 AI
T1218 · System Binary Proxy Execution T1531 · Account Access Removal T1059 · Command and Scripting InterpreterAffected Version Matrix 12
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| Linux | Linux | 86956e70761b3292156d668e87126844334dd71b< eb6cc898501a004c0fa8aab951351d9c959b91cc |
affected |
86956e70761b3292156d668e87126844334dd71b< 6a180adafc2a8a5fbe815985c71b2201e93ab5e1 |
affected | ||
86956e70761b3292156d668e87126844334dd71b< fc069d00a0dbef40042fd681554d48dcd5a1d524 |
affected | ||
86956e70761b3292156d668e87126844334dd71b< 13bfc94eef389bd664ffc67b00184919902c938a |
affected | ||
86956e70761b3292156d668e87126844334dd71b< 4400270ec0348d05dc0439d8f0130853ce7f9e20 |
affected | ||
5.15 |
affected | ||
< 5.15 |
unaffected | ||
6.6.157≤ 6.6.* |
unaffected | ||
| … +4 more rows | |||
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I. Basic Information for CVE-2026-89960
Vulnerability Information
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Vulnerability Title
s390/vfio-ap: fix stale pqap_hook pointer on error in vfio_ap_mdev_set_kvm()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
s390/vfio-ap: fix stale pqap_hook pointer on error in vfio_ap_mdev_set_kvm()
In vfio_ap_mdev_set_kvm(), kvm->arch.crypto.pqap_hook is set to
&matrix_mdev->pqap_hook before the update locks are acquired and the
mdev list is checked for a conflicting assignment. If another mdev is
already attached to the same KVM instance, the function returns -EPERM
without restoring the hook pointer, leaving kvm->arch.crypto.pqap_hook
pointing at the failing matrix_mdev instead of the mdev that legitimately
owns the KVM.
Since matrix_mdev->kvm is never set on this error path,
vfio_ap_mdev_unset_kvm() will not clean up the hook when matrix_mdev
is later closed. If matrix_mdev is subsequently freed, any PQAP
instruction executed by the guest will dereference the stale pointer
through pqap_hook_rwsem, resulting in a use-after-free.
Since kvm->arch.crypto.pqap_hook is only set in the vfio_ap_mdev_set_kvm()
function and is cleared in the vfio_ap_mdev_unset_kvm() function, a check
for 'kvm->arch.crypto.pqap_hook != NULL' is all that is needed to determine
whether it belongs to another mdev. This will alleviate the need to iterate
the matrix_dev->mdev_list list to see if the kvm object is assigned to
another mdev.This was introduced in v3 to alleviate the need to take the
mdevs_lock while iterating the list; however, this did not prevent a
potential race condition.
The pqap_hook_rwsem(write) is now performed inside
get_update_locks_for_kvm(), which is updated to acquire
pqap_hook_rwsem(write) between kvm->lock and mdevs_lock. This ordering
is consistent with the PQAP intercept path, which acquires pqap_hook_rwsem
in read mode while srcu is held under vcpu->mutex, establishing the
dependency: kvm->lock -> vcpu->mutex -> srcu -> pqap_hook_rwsem(read).
The pqap_hook_rwsem is now released inside the
release_update_locks_for_kvm(), which is updated to release
pqap_hook_rwsem(write) between mdevs_lock and kvm->lock.
Additionally, kvm_put_kvm() in vfio_ap_mdev_unset_kvm() is moved
after release_update_locks_for_kvm(). Previously it was called while
kvm->lock was held; if it were ever the last reference, kvm_destroy_vm()
would run under kvm->lock, which would deadlock.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Affected Products
II. Public POCs for CVE-2026-89960
| # | POC Description | Source Link | Shenlong Link |
|---|
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Other References for CVE-2026-89960 (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-2026-89914 | 9.3 CRITICAL | KVM: arm64: Sign-extend VA for range-based TLBI invalidation |
| 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 → →
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