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KVM: arm64: Fix uninitialized memcache pointer in user_mem_abort()

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Commit fce886a602 ("KVM: arm64: Plumb the pKVM MMU in KVM") made the
initialization of the local memcache variable in user_mem_abort()
conditional, leaving a codepath where it is used uninitialized via
kvm_pgtable_stage2_map().

This can fail on any path that requires a stage-2 allocation
without transition via a permission fault or dirty logging.

Fix this by making sure that memcache is always valid.

Fixes: fce886a602 ("KVM: arm64: Plumb the pKVM MMU in KVM")
Signed-off-by: Sebastian Ott <sebott@redhat.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/kvmarm/3f5db4c7-ccce-fb95-595c-692fa7aad227@redhat.com/
Link: https://lore.kernel.org/r/20250505173148.33900-1-sebott@redhat.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Sebastian Ott
2025-05-05 19:31:48 +02:00
committed by Oliver Upton
parent b4432656b3
commit 157dbc4a32
1 changed files with 8 additions and 5 deletions
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arch/arm64/kvm/mmu.c
+8 -5
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@@ -1501,6 +1501,11 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
return -EFAULT;
}
if (!is_protected_kvm_enabled())
memcache = &vcpu->arch.mmu_page_cache;
else
memcache = &vcpu->arch.pkvm_memcache;
/*
* Permission faults just need to update the existing leaf entry,
* and so normally don't require allocations from the memcache. The
@@ -1510,13 +1515,11 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
if (!fault_is_perm || (logging_active && write_fault)) {
int min_pages = kvm_mmu_cache_min_pages(vcpu->arch.hw_mmu);
if (!is_protected_kvm_enabled()) {
memcache = &vcpu->arch.mmu_page_cache;
if (!is_protected_kvm_enabled())
ret = kvm_mmu_topup_memory_cache(memcache, min_pages);
} else {
memcache = &vcpu->arch.pkvm_memcache;
else
ret = topup_hyp_memcache(memcache, min_pages);
}
if (ret)
return ret;
}