[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20180710180123.56461-3-mark.rutland@arm.com>
Date: Tue, 10 Jul 2018 19:01:23 +0100
From: Mark Rutland <mark.rutland@....com>
To: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc: catalin.marinas@....com, christoffer.dall@....com,
kvmarm@...ts.cs.columbia.edu, marc.zyngier@....com,
mark.rutland@....com, will.deacon@....com
Subject: [PATCH 2/2] 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@....com>
Cc: Christoffer Dall <christoffer.dall@....com>
Cc: Marc Zyngier <marc.zyngier@....com>
Cc: kvmarm@...ts.cs.columbia.edu
---
virt/kvm/arm/vgic/vgic-mmio-v2.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
index ffc587bf4742..64e571cc02df 100644
--- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
+++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
@@ -352,6 +352,9 @@ 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;
}
--
2.11.0
Powered by blists - more mailing lists