[PATCH 1/3] kvm: arm/arm64: Take mmap_sem in stage2_unmap_vm

From	Suzuki K Poulose <suzuki.poulose@arm.com>
Newsgroups	linux.kernel
Subject	[PATCH 1/3] kvm: arm/arm64: Take mmap_sem in stage2_unmap_vm
Date	2017-03-14 16:00 +0100
Message-ID	<tkW5z-1Ad-5@gated-at.bofh.it> (permalink)
References	<tkW5z-1Ad-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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From: Marc Zyngier <marc.zyngier@arm.com>

We don't hold the mmap_sem while searching for the VMAs when
we try to unmap each memslot for a VM. Fix this properly to
avoid unexpected results.

Fixes: commit 957db105c997 ("arm/arm64: KVM: Introduce stage2_unmap_vm")
Cc: stable@vger.kernel.org # v3.19+
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
 arch/arm/kvm/mmu.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 962616f..f2e2e0c 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -803,6 +803,7 @@ void stage2_unmap_vm(struct kvm *kvm)
 	int idx;
 
 	idx = srcu_read_lock(&kvm->srcu);
+	down_read(&current->mm->mmap_sem);
 	spin_lock(&kvm->mmu_lock);
 
 	slots = kvm_memslots(kvm);
@@ -810,6 +811,7 @@ void stage2_unmap_vm(struct kvm *kvm)
 		stage2_unmap_memslot(kvm, memslot);
 
 	spin_unlock(&kvm->mmu_lock);
+	up_read(&current->mm->mmap_sem);
 	srcu_read_unlock(&kvm->srcu, idx);
 }
 
-- 
2.7.4

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[PATCH 1/3] kvm: arm/arm64: Take mmap_sem in stage2_unmap_vm Suzuki K Poulose <suzuki.poulose@arm.com> - 2017-03-14 16:00 +0100
  Re: [PATCH 1/3] kvm: arm/arm64: Take mmap_sem in stage2_unmap_vm Christoffer Dall <cdall@linaro.org> - 2017-03-15 10:20 +0100
    Re: [PATCH 1/3] kvm: arm/arm64: Take mmap_sem in stage2_unmap_vm Marc Zyngier <marc.zyngier@arm.com> - 2017-03-15 10:40 +0100
      Re: [PATCH 1/3] kvm: arm/arm64: Take mmap_sem in stage2_unmap_vm Christoffer Dall <cdall@linaro.org> - 2017-03-15 12:10 +0100
    Re: [PATCH 1/3] kvm: arm/arm64: Take mmap_sem in stage2_unmap_vm Paolo Bonzini <pbonzini@redhat.com> - 2017-03-15 14:40 +0100

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