arm/arm64: KVM: Take mmap_sem in stage2_unmap_vm

[ Upstream commit 90f6e150e44a0dc3883110eeb3ab35d1be42b6bb ]

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+
Reviewed-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index e506389d02fbcf6f70689a5bceb6ef11dbc76c73..017d6d1e1766e4d2d5af348fb17af9ebbd96fed4 100644 (file)
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -760,6 +760,7 @@ 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);
@@ -767,6 +768,7 @@ 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);
 }