CVE-2026-53359

Summary

In the Linux kernel, the following vulnerability has been resolved:KVM: x86: Fix shadow paging use-after-free due to unexpected roleCommit 0cb2af2ea66ad ("KVM: x86: Fix shadow paging use-after-free due to unexpected GFN") fixed a shadow paging mismatch between stored and computed GFNs; the bug could be triggered by changing a PDE mapping from outside the guest, and then deleting a memslot. The rmap_remove() call would miss entries created after the PDE change because the GFN of the leaf SPTE does not match the GFN of the struct kvm_mmu_page.A similar hole however remains if the modified PDE points to a non-leaf page. In this case the gfn can be made to match, but the role does not match: the original large 2MB page creates a kvm_mmu_page with direct=1, while the new 4KB needs a kvm_mmu_page with direct=0. However, kvm_mmu_get_child_sp() does not compare the role, and therefore reuses the page.The next step is installing a leaf (4KB) SPTE on the new path which records an rmap entry under the gfn resolved by the walk. But when that child is zapped its parent kvm_mmu_page has direct=1 and kvm_mmu_page_get_gfn() computes the gfn for the 4KB page as sp->gfn + index instead of using sp->shadowed_translation[] (or sp->gfns[] in older kernels). It therefore fails to remove the recorded entry.When the memslot is dropped the shadow page is freed but the rmap entry survives, as in the scenario that was already fixed. Code that later walks that gfn (dirty logging, MMU notifier invalidation, and so on) dereferences an sptep that lies in the freed page, causing the use-after-free.

CWE-416Use After Free

Attack profile

Affected products

• Linux2032a93d66fa282ba0f2ea9152eeff9511fa9a96 to before 0b5e8ead71e683bcf6232db16234cf7e6d553a232032a93d66fa282ba0f2ea9152eeff9511fa9a96 to before b1337aae5e194324e4810d561764e7793f8b38642032a93d66fa282ba0f2ea9152eeff9511fa9a96 to before 9291654d69e08542de37755cebe4d5b02c3170d12032a93d66fa282ba0f2ea9152eeff9511fa9a96 to before 2ad3afa40ac6aa340dada122f9abfa46c0a6eb35
• Linux2.6.36

References