linux-kernel - [PATCH v2 05/13] KVM: x86: Protect ioapic_write

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Message-Id: <20191211204753.242298-6-pomonis@google.com>
Date:   Wed, 11 Dec 2019 12:47:45 -0800
From:   Marios Pomonis <pomonis@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, rkrcmar@...hat.com,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Nick Finco <nifi@...gle.com>, Andrew Honig <ahonig@...gle.com>,
        Marios Pomonis <pomonis@...gle.com>, stable@...r.kernel.org
Subject: [PATCH v2 05/13] KVM: x86: Protect ioapic_write_indirect() from
 Spectre-v1/L1TF attacks

This fixes a Spectre-v1/L1TF vulnerability in ioapic_write_indirect().
This function contains index computations based on the
(attacker-controlled) IOREGSEL register.

This patch depends on patch
"KVM: x86: Protect ioapic_read_indirect() from Spectre-v1/L1TF attacks".

Fixes: commit 70f93dae32ac ("KVM: Use temporary variable to shorten lines.")

Signed-off-by: Nick Finco <nifi@...gle.com>
Signed-off-by: Marios Pomonis <pomonis@...gle.com>
Reviewed-by: Andrew Honig <ahonig@...gle.com>
Cc: stable@...r.kernel.org
---
 arch/x86/kvm/ioapic.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
index 0c672eefaabe..8aa58727045e 100644
--- a/arch/x86/kvm/ioapic.c
+++ b/arch/x86/kvm/ioapic.c
@@ -294,6 +294,7 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
 
 		if (index >= IOAPIC_NUM_PINS)
 			return;
+		index = array_index_nospec(index, IOAPIC_NUM_PINS);
 		e = &ioapic->redirtbl[index];
 		mask_before = e->fields.mask;
 		/* Preserve read-only fields */
-- 
2.24.0.525.g8f36a354ae-goog