* [PATCH] KVM: arm/arm64: vgic: fix off-by-one bug in vgic_get_irq()
@ 2018-12-12 20:11 ` Gustavo A. R. Silva
0 siblings, 0 replies; 5+ messages in thread
From: Gustavo A. R. Silva @ 2018-12-12 20:11 UTC (permalink / raw)
To: Mark Rutland, Christoffer Dall, Marc Zyngier, Will Deacon
Cc: linux-arm-kernel, kvmarm, linux-kernel, Gustavo A. R. Silva
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>
---
virt/kvm/arm/vgic/vgic.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 50e25438fb3c..5db40696055a 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -103,13 +103,13 @@ 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];
}
/* SPIs */
if (intid <= VGIC_MAX_SPI) {
- intid = array_index_nospec(intid, VGIC_MAX_SPI);
+ intid = array_index_nospec(intid, VGIC_MAX_SPI + 1);
return &kvm->arch.vgic.spis[intid - VGIC_NR_PRIVATE_IRQS];
}
--
2.17.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH] KVM: arm/arm64: vgic: fix off-by-one bug in vgic_get_irq()
@ 2018-12-12 20:11 ` Gustavo A. R. Silva
0 siblings, 0 replies; 5+ messages in thread
From: Gustavo A. R. Silva @ 2018-12-12 20:11 UTC (permalink / raw)
To: Mark Rutland, Christoffer Dall, Marc Zyngier, Will Deacon
Cc: Gustavo A. R. Silva, kvmarm, linux-arm-kernel, linux-kernel
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>
---
virt/kvm/arm/vgic/vgic.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 50e25438fb3c..5db40696055a 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -103,13 +103,13 @@ 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];
}
/* SPIs */
if (intid <= VGIC_MAX_SPI) {
- intid = array_index_nospec(intid, VGIC_MAX_SPI);
+ intid = array_index_nospec(intid, VGIC_MAX_SPI + 1);
return &kvm->arch.vgic.spis[intid - VGIC_NR_PRIVATE_IRQS];
}
--
2.17.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH] KVM: arm/arm64: vgic: fix off-by-one bug in vgic_get_irq()
@ 2018-12-12 20:11 ` Gustavo A. R. Silva
0 siblings, 0 replies; 5+ messages in thread
From: Gustavo A. R. Silva @ 2018-12-12 20:11 UTC (permalink / raw)
To: Mark Rutland, Christoffer Dall, Marc Zyngier, Will Deacon
Cc: Gustavo A. R. Silva, kvmarm, linux-arm-kernel, linux-kernel
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>
---
virt/kvm/arm/vgic/vgic.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 50e25438fb3c..5db40696055a 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -103,13 +103,13 @@ 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];
}
/* SPIs */
if (intid <= VGIC_MAX_SPI) {
- intid = array_index_nospec(intid, VGIC_MAX_SPI);
+ intid = array_index_nospec(intid, VGIC_MAX_SPI + 1);
return &kvm->arch.vgic.spis[intid - VGIC_NR_PRIVATE_IRQS];
}
--
2.17.1
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] KVM: arm/arm64: vgic: fix off-by-one bug in vgic_get_irq()
2018-12-12 20:11 ` Gustavo A. R. Silva
@ 2018-12-13 10:52 ` Marc Zyngier
-1 siblings, 0 replies; 5+ messages in thread
From: Marc Zyngier @ 2018-12-13 10:52 UTC (permalink / raw)
To: Gustavo A. R. Silva, Mark Rutland, Christoffer Dall, Will Deacon
Cc: kvmarm, linux-arm-kernel, linux-kernel
Hi Gustavo,
On 12/12/2018 20:11, Gustavo A. R. Silva wrote:
> 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>
> ---
> virt/kvm/arm/vgic/vgic.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
> index 50e25438fb3c..5db40696055a 100644
> --- a/virt/kvm/arm/vgic/vgic.c
> +++ b/virt/kvm/arm/vgic/vgic.c
> @@ -103,13 +103,13 @@ 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];
> }
>
> /* SPIs */
> if (intid <= VGIC_MAX_SPI) {
> - intid = array_index_nospec(intid, VGIC_MAX_SPI);
> + intid = array_index_nospec(intid, VGIC_MAX_SPI + 1);
> return &kvm->arch.vgic.spis[intid - VGIC_NR_PRIVATE_IRQS];
> }
>
>
That's a good one. Out of curiosity, how did you find it?
Thanks,
M.
--
Jazz is not dead. It just smells funny...
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] KVM: arm/arm64: vgic: fix off-by-one bug in vgic_get_irq()
@ 2018-12-13 10:52 ` Marc Zyngier
0 siblings, 0 replies; 5+ messages in thread
From: Marc Zyngier @ 2018-12-13 10:52 UTC (permalink / raw)
To: Gustavo A. R. Silva, Mark Rutland, Christoffer Dall, Will Deacon
Cc: kvmarm, linux-arm-kernel, linux-kernel
Hi Gustavo,
On 12/12/2018 20:11, Gustavo A. R. Silva wrote:
> 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>
> ---
> virt/kvm/arm/vgic/vgic.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
> index 50e25438fb3c..5db40696055a 100644
> --- a/virt/kvm/arm/vgic/vgic.c
> +++ b/virt/kvm/arm/vgic/vgic.c
> @@ -103,13 +103,13 @@ 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];
> }
>
> /* SPIs */
> if (intid <= VGIC_MAX_SPI) {
> - intid = array_index_nospec(intid, VGIC_MAX_SPI);
> + intid = array_index_nospec(intid, VGIC_MAX_SPI + 1);
> return &kvm->arch.vgic.spis[intid - VGIC_NR_PRIVATE_IRQS];
> }
>
>
That's a good one. Out of curiosity, how did you find it?
Thanks,
M.
--
Jazz is not dead. It just smells funny...
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2018-12-13 10:53 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-12-12 20:11 [PATCH] KVM: arm/arm64: vgic: fix off-by-one bug in vgic_get_irq() Gustavo A. R. Silva
2018-12-12 20:11 ` Gustavo A. R. Silva
2018-12-12 20:11 ` Gustavo A. R. Silva
2018-12-13 10:52 ` Marc Zyngier
2018-12-13 10:52 ` Marc Zyngier
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.