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KVM: x86: Refactor picdev_write() to prevent Spectre-v1/L1TF attacks

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This fixes a Spectre-v1/L1TF vulnerability in picdev_write().
It replaces index computations based on the (attacked-controlled) port
number with constants through a minor refactoring.

Fixes: 85f455f7ddbe ("KVM: Add support for in-kernel PIC emulation")

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>
This commit is contained in:
Marios Pomonis 2019-12-11 12:47:43 -08:00 committed by Paolo Bonzini
parent 8618793750
commit 14e32321f3
1 changed files with 5 additions and 1 deletions
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6
arch/x86/kvm/i8259.c
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@ -460,10 +460,14 @@ static int picdev_write(struct kvm_pic *s,
switch (addr) {
case 0x20:
case 0x21:
pic_lock(s);
pic_ioport_write(&s->pics[0], addr, data);
pic_unlock(s);
break;
case 0xa0:
case 0xa1:
pic_lock(s);
pic_ioport_write(&s->pics[addr >> 7], addr, data);
pic_ioport_write(&s->pics[1], addr, data);
pic_unlock(s);
break;
case 0x4d0: