| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 71/91] KVM: x86: Protect kvm_lapic_reg_write() from Spectre-v1/L1TF attacks | Date | Thu, 13 Feb 2020 07:20:28 -0800 |
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From: Marios Pomonis <pomonis@google.com>
[ Upstream commit 4bf79cb089f6b1c6c632492c0271054ce52ad766 ]
This fixes a Spectre-v1/L1TF vulnerability in kvm_lapic_reg_write(). This function contains index computations based on the (attacker-controlled) MSR number.
Fixes: 0105d1a52640 ("KVM: x2apic interface to lapic")
Signed-off-by: Nick Finco <nifi@google.com> Signed-off-by: Marios Pomonis <pomonis@google.com> Reviewed-by: Andrew Honig <ahonig@google.com> Cc: stable@vger.kernel.org Reviewed-by: Jim Mattson <jmattson@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> --- arch/x86/kvm/lapic.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 3c70f6c76d3a2..ce8c4ae25c157 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -36,6 +36,7 @@ #include <asm/delay.h> #include <linux/atomic.h> #include <linux/jump_label.h> +#include <linux/nospec.h> #include "kvm_cache_regs.h" #include "irq.h" #include "trace.h" @@ -1432,15 +1433,21 @@ static int apic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val) case APIC_LVTTHMR: case APIC_LVTPC: case APIC_LVT1: - case APIC_LVTERR: + case APIC_LVTERR: { /* TODO: Check vector */ + size_t size; + u32 index; + if (!kvm_apic_sw_enabled(apic)) val |= APIC_LVT_MASKED; - val &= apic_lvt_mask[(reg - APIC_LVTT) >> 4]; + size = ARRAY_SIZE(apic_lvt_mask); + index = array_index_nospec( + (reg - APIC_LVTT) >> 4, size); + val &= apic_lvt_mask[index]; apic_set_reg(apic, reg, val); - break; + } case APIC_LVTT: if (!kvm_apic_sw_enabled(apic)) -- 2.20.1
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