patches/kernel/0232-kvm-vmx-Scrub-hardware-GPRs-at-VM-exit.patch

   1 From c59a61438e9a8f24a50171ac9d3b98e8f3719d07 Mon Sep 17 00:00:00 2001
   2 From: Jim Mattson <jmattson@google.com>
   3 Date: Wed, 3 Jan 2018 14:31:38 -0800
   4 Subject: [PATCH 232/241] kvm: vmx: Scrub hardware GPRs at VM-exit
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 Guest GPR values are live in the hardware GPRs at VM-exit.  Do not
  10 leave any guest values in hardware GPRs after the guest GPR values are
  11 saved to the vcpu_vmx structure.
  12
  13 This is a partial mitigation for CVE 2017-5715 and CVE 2017-5753.
  14 Specifically, it defeats the Project Zero PoC for CVE 2017-5715.
  15
  16 Suggested-by: Eric Northup <digitaleric@google.com>
  17 Signed-off-by: Jim Mattson <jmattson@google.com>
  18 Reviewed-by: Eric Northup <digitaleric@google.com>
  19 Reviewed-by: Benjamin Serebrin <serebrin@google.com>
  20 Reviewed-by: Andrew Honig <ahonig@google.com>
  21 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  22 ---
  23  arch/x86/kvm/vmx.c | 14 +++++++++++++-
  24  1 file changed, 13 insertions(+), 1 deletion(-)
  25
  26 diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
  27 index d61986a36575..9b4256fd589a 100644
  28 --- a/arch/x86/kvm/vmx.c
  29 +++ b/arch/x86/kvm/vmx.c
  30 @@ -9140,6 +9140,7 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
  31                 /* Save guest registers, load host registers, keep flags */
  32                 "mov %0, %c[wordsize](%%" _ASM_SP ") \n\t"
  33                 "pop %0 \n\t"
  34 +               "setbe %c[fail](%0)\n\t"
  35                 "mov %%" _ASM_AX ", %c[rax](%0) \n\t"
  36                 "mov %%" _ASM_BX ", %c[rbx](%0) \n\t"
  37                 __ASM_SIZE(pop) " %c[rcx](%0) \n\t"
  38 @@ -9156,12 +9157,23 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
  39                 "mov %%r13, %c[r13](%0) \n\t"
  40                 "mov %%r14, %c[r14](%0) \n\t"
  41                 "mov %%r15, %c[r15](%0) \n\t"
  42 +               "xor %%r8d,  %%r8d \n\t"
  43 +               "xor %%r9d,  %%r9d \n\t"
  44 +               "xor %%r10d, %%r10d \n\t"
  45 +               "xor %%r11d, %%r11d \n\t"
  46 +               "xor %%r12d, %%r12d \n\t"
  47 +               "xor %%r13d, %%r13d \n\t"
  48 +               "xor %%r14d, %%r14d \n\t"
  49 +               "xor %%r15d, %%r15d \n\t"
  50  #endif
  51                 "mov %%cr2, %%" _ASM_AX "   \n\t"
  52                 "mov %%" _ASM_AX ", %c[cr2](%0) \n\t"
  53
  54 +               "xor %%eax, %%eax \n\t"
  55 +               "xor %%ebx, %%ebx \n\t"
  56 +               "xor %%esi, %%esi \n\t"
  57 +               "xor %%edi, %%edi \n\t"
  58                 "pop  %%" _ASM_BP "; pop  %%" _ASM_DX " \n\t"
  59 -               "setbe %c[fail](%0) \n\t"
  60                 ".pushsection .rodata \n\t"
  61                 ".global vmx_return \n\t"
  62                 "vmx_return: " _ASM_PTR " 2b \n\t"
  63 --
  64 2.14.2
  65