diff options
| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2018-12-12 14:11:23 -0600 |
|---|---|---|
| committer | Marc Zyngier <marc.zyngier@arm.com> | 2018-12-19 17:46:07 +0000 |
| commit | c23b2e6fc4ca346018618266bcabd335c0a8a49e (patch) | |
| tree | 3bae71bd9b462b24f2365b4fbe47c1af537cb6fd /virt | |
| parent | bea2ef803ade3359026d5d357348842bca9edcf1 (diff) | |
| download | lwn-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.c | 2 |
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]; } |