git.ipfire.org Git - thirdparty/kernel/stable-queue.git/blob

   1 From 25a5edea71b7c154b6a0b8cec14c711cafa31d26 Mon Sep 17 00:00:00 2001
   2 From: Marios Pomonis <pomonis@google.com>
   3 Date: Wed, 11 Dec 2019 12:47:47 -0800
   4 Subject: KVM: x86: Protect MSR-based index computations in fixed_msr_to_seg_unit() from Spectre-v1/L1TF attacks
   5
   6 From: Marios Pomonis <pomonis@google.com>
   7
   8 commit 25a5edea71b7c154b6a0b8cec14c711cafa31d26 upstream.
   9
  10 This fixes a Spectre-v1/L1TF vulnerability in fixed_msr_to_seg_unit().
  11 This function contains index computations based on the
  12 (attacker-controlled) MSR number.
  13
  14 Fixes: de9aef5e1ad6 ("KVM: MTRR: introduce fixed_mtrr_segment table")
  15
  16 Signed-off-by: Nick Finco <nifi@google.com>
  17 Signed-off-by: Marios Pomonis <pomonis@google.com>
  18 Reviewed-by: Andrew Honig <ahonig@google.com>
  19 Cc: stable@vger.kernel.org
  20 Reviewed-by: Jim Mattson <jmattson@google.com>
  21 Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
  22 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  23
  24 ---
  25  arch/x86/kvm/mtrr.c |    8 ++++++--
  26  1 file changed, 6 insertions(+), 2 deletions(-)
  27
  28 --- a/arch/x86/kvm/mtrr.c
  29 +++ b/arch/x86/kvm/mtrr.c
  30 @@ -202,11 +202,15 @@ static bool fixed_msr_to_seg_unit(u32 ms
  31                 break;
  32         case MSR_MTRRfix16K_80000 ... MSR_MTRRfix16K_A0000:
  33                 *seg = 1;
  34 -               *unit = msr - MSR_MTRRfix16K_80000;
  35 +               *unit = array_index_nospec(
  36 +                       msr - MSR_MTRRfix16K_80000,
  37 +                       MSR_MTRRfix16K_A0000 - MSR_MTRRfix16K_80000 + 1);
  38                 break;
  39         case MSR_MTRRfix4K_C0000 ... MSR_MTRRfix4K_F8000:
  40                 *seg = 2;
  41 -               *unit = msr - MSR_MTRRfix4K_C0000;
  42 +               *unit = array_index_nospec(
  43 +                       msr - MSR_MTRRfix4K_C0000,
  44 +                       MSR_MTRRfix4K_F8000 - MSR_MTRRfix4K_C0000 + 1);
  45                 break;
  46         default:
  47                 return false;