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

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Date:   Fri,  2 Jun 2023 16:32:47 -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: [PATCH v3 0/3]  KVM: x86: Out-of-bounds access in kvm_recalculate_phys_map()

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.

v3:
 - s/race/test for the new test file
 - Use kvm_vm_free() instead of kvm_vm_release() in the test
 - Fix a few typos in the test

v2: https://lore.kernel.org/all/20230526235048.2842761-1-seanjc@google.com

v1: https://lore.kernel.org/all/20230525183347.2562472-1-mhal@rbox.co

Michal Luczaj (1):
  KVM: selftests: Add test for race in kvm_recalculate_apic_map()

Sean Christopherson (2):
  KVM: x86: Bail from kvm_recalculate_phys_map() if x2APIC ID is
    out-of-bounds
  KVM: x86: Retry APIC optimized map recalc if vCPU is added/enabled

 arch/x86/kvm/lapic.c                          | 49 ++++++++++--
 tools/testing/selftests/kvm/Makefile          |  1 +
 .../kvm/x86_64/recalc_apic_map_test.c         | 74 +++++++++++++++++++
 3 files changed, 118 insertions(+), 6 deletions(-)
 create mode 100644 tools/testing/selftests/kvm/x86_64/recalc_apic_map_test.c


base-commit: 39428f6ea9eace95011681628717062ff7f5eb5f
-- 
2.41.0.rc2.161.g9c6817b8e7-goog