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

From: Suzuki K Poulose
Date: Tue Mar 14 2017 - 10:54:59 EST


From: Marc Zyngier <marc.zyngier@xxxxxxx>

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@xxxxxxxxxxxxxxx # v3.19+
Cc: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
---
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