[kernel] KVM: PPC: Fix incorrect guest-to-user-translation error handling
diff mbox series

Message ID 20190826045520.92153-1-aik@ozlabs.ru
State Accepted
Headers show
Series
  • [kernel] KVM: PPC: Fix incorrect guest-to-user-translation error handling
Related show

Commit Message

Alexey Kardashevskiy Aug. 26, 2019, 4:55 a.m. UTC
H_PUT_TCE_INDIRECT handlers receive a page with up to 512 TCEs from
a guest. Although we verify correctness of TCEs before we do anything
with the existing tables, there is a small window when a check in
kvmppc_tce_validate might pass and right after that the guest alters
the page with TCEs which can cause early exit from the handler and
leave srcu_read_lock(&vcpu->kvm->srcu) (virtual mode) or lock_rmap(rmap)
(real mode) locked.

This fixes the bug by jumping to the common exit code with an appropriate
unlock.

Fixes: 121f80ba68f1 ("KVM: PPC: VFIO: Add in-kernel acceleration for VFIO")
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 arch/powerpc/kvm/book3s_64_vio.c    | 6 ++++--
 arch/powerpc/kvm/book3s_64_vio_hv.c | 6 ++++--
 2 files changed, 8 insertions(+), 4 deletions(-)

Comments

Michael Ellerman Sept. 2, 2019, 3:06 a.m. UTC | #1
On Mon, 2019-08-26 at 04:55:20 UTC, Alexey Kardashevskiy wrote:
> H_PUT_TCE_INDIRECT handlers receive a page with up to 512 TCEs from
> a guest. Although we verify correctness of TCEs before we do anything
> with the existing tables, there is a small window when a check in
> kvmppc_tce_validate might pass and right after that the guest alters
> the page with TCEs which can cause early exit from the handler and
> leave srcu_read_lock(&vcpu->kvm->srcu) (virtual mode) or lock_rmap(rmap)
> (real mode) locked.
> 
> This fixes the bug by jumping to the common exit code with an appropriate
> unlock.
> 
> Fixes: 121f80ba68f1 ("KVM: PPC: VFIO: Add in-kernel acceleration for VFIO")
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Applied to powerpc topic/ppc-kvm, thanks.

https://git.kernel.org/powerpc/c/4f916593be9da38c5cf0d3a5c386b57beb70f422

cheers

Patch
diff mbox series

diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c
index e99a14798ab0..c4b606fe73eb 100644
--- a/arch/powerpc/kvm/book3s_64_vio.c
+++ b/arch/powerpc/kvm/book3s_64_vio.c
@@ -660,8 +660,10 @@  long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu,
 		}
 		tce = be64_to_cpu(tce);
 
-		if (kvmppc_tce_to_ua(vcpu->kvm, tce, &ua))
-			return H_PARAMETER;
+		if (kvmppc_tce_to_ua(vcpu->kvm, tce, &ua)) {
+			ret = H_PARAMETER;
+			goto unlock_exit;
+		}
 
 		list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
 			ret = kvmppc_tce_iommu_map(vcpu->kvm, stt,
diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c
index f50bbeedfc66..b4f20f13b860 100644
--- a/arch/powerpc/kvm/book3s_64_vio_hv.c
+++ b/arch/powerpc/kvm/book3s_64_vio_hv.c
@@ -556,8 +556,10 @@  long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu,
 		unsigned long tce = be64_to_cpu(((u64 *)tces)[i]);
 
 		ua = 0;
-		if (kvmppc_rm_tce_to_ua(vcpu->kvm, tce, &ua, NULL))
-			return H_PARAMETER;
+		if (kvmppc_rm_tce_to_ua(vcpu->kvm, tce, &ua, NULL)) {
+			ret = H_PARAMETER;
+			goto unlock_exit;
+		}
 
 		list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
 			ret = kvmppc_rm_tce_iommu_map(vcpu->kvm, stt,