linux-kernel - Re: [PATCH v3 0/3] KVM: x86: Out-of-bounds access in kvm_recalculate_phys

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Date:   Fri,  2 Jun 2023 17:52:30 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Michal Luczaj <mhal@...x.co>
Subject: Re: [PATCH v3 0/3] KVM: x86: Out-of-bounds access in kvm_recalculate_phys_map()

On Fri, 02 Jun 2023 16:32:47 -0700, Sean Christopherson wrote:
> In Michal's words...
> 
> kvm_recalculate_apic_map() creates the APIC map iterating over the list of
> vCPUs twice. First to find the max APIC ID and allocate a max-sized buffer,
> then again, calling kvm_recalculate_phys_map() for each vCPU. This opens a
> race window: value of max APIC ID can increase _after_ the buffer was
> allocated.
> 
> [...]

Applied 1 and 3 to kvm-x86 fixes (for 6.4), figuring out how to deal with the
dependencies get #2 into 6.5 is a future problem.

[1/3] KVM: x86: Bail from kvm_recalculate_phys_map() if x2APIC ID is out-of-bounds
      https://github.com/kvm-x86/linux/commit/4364b287982b
[2/3] ...
[3/3] KVM: selftests: Add test for race in kvm_recalculate_apic_map()
      https://github.com/kvm-x86/linux/commit/47d2804bc99c

--
https://github.com/kvm-x86/linux/tree/next
https://github.com/kvm-x86/linux/tree/fixes