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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Nick Finco <nifi@google.com>,
        Marios Pomonis <pomonis@google.com>,
        Andrew Honig <ahonig@google.com>,
        Jim Mattson <jmattson@google.com>,
        Paolo Bonzini <pbonzini@redhat.com>
Subject: [PATCH 5.5 233/367] KVM: x86: Protect ioapic_write_indirect() from Spectre-v1/L1TF attacks
Date:   Mon, 10 Feb 2020 04:32:26 -0800
Message-Id: <20200210122445.722731428@linuxfoundation.org>
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From: Marios Pomonis <pomonis@google.com>

commit 670564559ca35b439c8d8861fc399451ddf95137 upstream.

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

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/kvm/ioapic.c |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/x86/kvm/ioapic.c
+++ b/arch/x86/kvm/ioapic.c
@@ -292,6 +292,7 @@ static void ioapic_write_indirect(struct
 
 		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 */