KVM: x86/mmu: Fix use-after-free on vendor module reload

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-68428
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-10 13:20:36 UTC
Updated2026-08-10 13:20:36 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: Fix use-after-free on vendor module reload mmu_destroy_caches() destroys pte_list_desc_cache and mmu_page_header_cache, but leaves both pointers unchanged. The pointers live in kvm.ko, and therefore survive when a vendor module is unloaded while kvm.ko remains loaded. If creation of pte_list_desc_cache fails during a subsequent vendor module load, its assignment sets pte_list_desc_cache to NULL and the error path calls mmu_destroy_caches(). mmu_page_header_cache still points to the cache destroyed during the preceding vendor module unload. Passing that stale pointer to kmem_cache_destroy() causes a slab use-after-free. Reproduce the issue on a v7.1.3 kernel with CONFIG_KASAN=y, CONFIG_KASAN_GENERIC=y, CONFIG_KVM=m, and CONFIG_KVM_INTEL=m. A one-shot test hook forces pte_list_desc_cache to NULL on the second invocation of kvm_mmu_vendor_module_init(): 1. Load kvm.ko and kvm-intel.ko, creating both caches. 2. Unload only kvm_intel, leaving kvm.ko loaded. 3. Reload kvm_intel and force initialization through the -ENOMEM path. KASAN reports: BUG: KASAN: slab-use-after-free in kvm_mmu_vendor_module_init+0x5b/0x170 [kvm] ... kmem_cache_destroy+0x21/0x1d0 kvm_mmu_vendor_module_init+0x5b/0x170 [kvm] ... Allocated by task 16817: __kmem_cache_create_args+0x12c/0x3b0 __kmem_cache_create.constprop.0+0xb6/0xf0 [kvm] kvm_mmu_vendor_module_init+0x13b/0x170 [kvm] ... Freed by task 16820: kmem_cache_destroy+0x117/0x1d0 kvm_mmu_vendor_module_exit+0x21/0x30 [kvm] Clear both pointers immediately after destroying their caches so that the stored state reflects the caches' lifetime and repeated cleanup is safe. With the fix applied, the same injected vendor module reload fails with -ENOMEM as expected and produces no KASAN report.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected cb498ea2ce1d3f3c0bc0a2522241dca10263e437 6f4be73880302d5642c83a0813fdfe1f5fd4b6e3 git Not specified
CNA Linux Linux affected cb498ea2ce1d3f3c0bc0a2522241dca10263e437 32b9f89ed9e6d7a45075d64089c254a7f6e13695 git Not specified
CNA Linux Linux affected cb498ea2ce1d3f3c0bc0a2522241dca10263e437 ec9daa8fd1b6f45545c9839dca55bd867fad9e13 git Not specified
CNA Linux Linux affected cb498ea2ce1d3f3c0bc0a2522241dca10263e437 43cfb20d62ffe49626d62beecfc32eb6f262191c git Not specified
CNA Linux Linux affected cb498ea2ce1d3f3c0bc0a2522241dca10263e437 52f2f7c30126037975389aa04d24c506a5177c35 git Not specified
CNA Linux Linux affected 2.6.25 Not specified
CNA Linux Linux unaffected 2.6.25 semver Not specified
CNA Linux Linux unaffected 6.6.148 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.101 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.42 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.6 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2-rc5 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/43cfb20d62ffe49626d62beecfc32eb6f262191c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/32b9f89ed9e6d7a45075d64089c254a7f6e13695 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6f4be73880302d5642c83a0813fdfe1f5fd4b6e3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/52f2f7c30126037975389aa04d24c506a5177c35 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ec9daa8fd1b6f45545c9839dca55bd867fad9e13 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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