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authorGustavo A. R. Silva <gustavo@embeddedor.com>2018-12-12 14:11:23 -0600
committerMarc Zyngier <marc.zyngier@arm.com>2018-12-19 17:46:07 +0000
commitc23b2e6fc4ca346018618266bcabd335c0a8a49e (patch)
tree3bae71bd9b462b24f2365b4fbe47c1af537cb6fd /virt
parentbea2ef803ade3359026d5d357348842bca9edcf1 (diff)
downloadlwn-c23b2e6fc4ca346018618266bcabd335c0a8a49e.tar.gz
lwn-c23b2e6fc4ca346018618266bcabd335c0a8a49e.zip
KVM: arm/arm64: vgic: Fix off-by-one bug in vgic_get_irq()
When using the nospec API, it should be taken into account that: "...if the CPU speculates past the bounds check then * array_index_nospec() will clamp the index within the range of [0, * size)." The above is part of the header for macro array_index_nospec() in linux/nospec.h Now, in this particular case, if intid evaluates to exactly VGIC_MAX_SPI or to exaclty VGIC_MAX_PRIVATE, the array_index_nospec() macro ends up returning VGIC_MAX_SPI - 1 or VGIC_MAX_PRIVATE - 1 respectively, instead of VGIC_MAX_SPI or VGIC_MAX_PRIVATE, which, based on the original logic: /* SGIs and PPIs */ if (intid <= VGIC_MAX_PRIVATE) return &vcpu->arch.vgic_cpu.private_irqs[intid]; /* SPIs */ if (intid <= VGIC_MAX_SPI) return &kvm->arch.vgic.spis[intid - VGIC_NR_PRIVATE_IRQS]; are valid values for intid. Fix this by calling array_index_nospec() macro with VGIC_MAX_PRIVATE + 1 and VGIC_MAX_SPI + 1 as arguments for its parameter size. Fixes: 41b87599c743 ("KVM: arm/arm64: vgic: fix possible spectre-v1 in vgic_get_irq()") Cc: stable@vger.kernel.org Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> [dropped the SPI part which was fixed separately] Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/arm/vgic/vgic.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 8ab0491bcc94..f884a54b2601 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -103,7 +103,7 @@ struct vgic_irq *vgic_get_irq(struct kvm *kvm, struct kvm_vcpu *vcpu,
{
/* SGIs and PPIs */
if (intid <= VGIC_MAX_PRIVATE) {
- intid = array_index_nospec(intid, VGIC_MAX_PRIVATE);
+ intid = array_index_nospec(intid, VGIC_MAX_PRIVATE + 1);
return &vcpu->arch.vgic_cpu.private_irqs[intid];
}