ACK: [SRU][N:hwe-6.17][PATCH 0/1] CVE-2026-53359

[Alessio Faina]

On Wed, Jul 22, 2026 at 08:03:03PM +0300, Cengiz Can via kernel-team wrote:
> https://ubuntu.com/security/CVE-2026-53359
> 
> [ Impact ]
> 
> A second use-after-free in the same KVM x86 shadow MMU path. When
> kvm_mmu_get_child_sp() found a present, non-large SPTE it reused the child
> shadow page without checking the page role, so a guest could attach a
> shadow page under a mismatched role and leave a stale child shadow page
> that is later freed and used again.
> 
> [ Fix ]
> 
> noble/linux-hwe-6.17: clean cherry-pick
> 
> This fix depends on the CVE-2026-46113 fix (commit 0cb2af2ea66ad, "KVM:
> x86: Fix shadow paging use-after-free due to unexpected GFN"), sent
> separately, which must be applied first. That commit rewrites
> __link_shadow_page() to zap a present non-leaf SPTE; without it, applying
> this role check alone would trade one use-after-free for another.
> 
> [ Test Plan ]
> 
> Build tested only (CBD).
> 
> [ Where Problems Could Occur ]
> 
> The change is in the x86 KVM shadow MMU (arch/x86/kvm/mmu/mmu.c), the child
> shadow-page linking path. A mistake could affect shadow or nested paging
> guests. This is a clean pick of the upstream fix.
> 
> -- 
> kernel-team mailing list
> kernel-team at lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team

Acked-by: Alessio Faina <alessio.faina at canonical.com>