* [PATCH 4.18 063/235] KVM: arm/arm64: vgic: Fix possible spectre-v1 write in vgic_mmio_write_apr()
[not found] <20180924113103.999624566@linuxfoundation.org>
@ 2018-09-24 11:50 ` Greg Kroah-Hartman
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From: Greg Kroah-Hartman @ 2018-09-24 11:50 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Mark Rutland, Christoffer Dall,
Marc Zyngier, kvmarm, Sasha Levin
4.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mark Rutland <mark.rutland@arm.com>
[ Upstream commit 6b8b9a48545e08345b8ff77c9fd51b1aebdbefb3 ]
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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
virt/kvm/arm/vgic/vgic-mmio-v2.c | 3 +++
1 file changed, 3 insertions(+)
--- 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 k
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;
}
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