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| author | Mark Rutland <mark.rutland@arm.com> | 2018-07-10 19:01:23 +0100 |
|---|---|---|
| committer | Marc Zyngier <marc.zyngier@arm.com> | 2018-07-24 13:53:54 +0100 |
| commit | 6b8b9a48545e08345b8ff77c9fd51b1aebdbefb3 (patch) | |
| tree | 03edc816580eadf5c76be597c86eeec9a9aea11a /virt/kvm/arm/vgic | |
| parent | b0960b9569db6b2fe8a75967d47b9dcdeb44016b (diff) | |
| download | lwn-6b8b9a48545e08345b8ff77c9fd51b1aebdbefb3.tar.gz lwn-6b8b9a48545e08345b8ff77c9fd51b1aebdbefb3.zip | |
KVM: arm/arm64: vgic: Fix possible spectre-v1 write in vgic_mmio_write_apr()
It's possible for userspace to control n. Sanitize n when using it as an
array index, to inhibit the potential spectre-v1 write gadget.
Note that while it appears that n must be bound to the interval [0,3]
due to the way it is extracted from addr, we cannot guarantee that
compiler transformations (and/or future refactoring) will ensure this is
the case, and given this is a slow path it's better to always perform
the masking.
Found by smatch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Christoffer Dall <christoffer.dall@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: kvmarm@lists.cs.columbia.edu
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Diffstat (limited to 'virt/kvm/arm/vgic')
| -rw-r--r-- | virt/kvm/arm/vgic/vgic-mmio-v2.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c index 26654f4140ed..738b65d2d0e7 100644 --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c @@ -399,6 +399,9 @@ static void vgic_mmio_write_apr(struct kvm_vcpu *vcpu, if (n > vgic_v3_max_apr_idx(vcpu)) return; + + n = array_index_nospec(n, 4); + /* GICv3 only uses ICH_AP1Rn for memory mapped (GICv2) guests */ vgicv3->vgic_ap1r[n] = val; } |