patches/kernel/0093-x86-entry-64-Use-POP-instead-of-MOV-to-restore-regs-.patch

   1 From c801c4e1ba695ba230e97f626abaeb0c16393b09 Mon Sep 17 00:00:00 2001
   2 From: Andy Lutomirski <luto@kernel.org>
   3 Date: Thu, 2 Nov 2017 00:59:05 -0700
   4 Subject: [PATCH 093/233] x86/entry/64: Use POP instead of MOV to restore regs
   5  on NMI return
   6 MIME-Version: 1.0
   7 Content-Type: text/plain; charset=UTF-8
   8 Content-Transfer-Encoding: 8bit
   9
  10 CVE-2017-5754
  11
  12 This gets rid of the last user of the old RESTORE_..._REGS infrastructure.
  13
  14 Signed-off-by: Andy Lutomirski <luto@kernel.org>
  15 Cc: Borislav Petkov <bpetkov@suse.de>
  16 Cc: Brian Gerst <brgerst@gmail.com>
  17 Cc: Dave Hansen <dave.hansen@intel.com>
  18 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  19 Cc: Peter Zijlstra <peterz@infradead.org>
  20 Cc: Thomas Gleixner <tglx@linutronix.de>
  21 Link: http://lkml.kernel.org/r/652a260f17a160789bc6a41d997f98249b73e2ab.1509609304.git.luto@kernel.org
  22 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  23 (cherry picked from commit 471ee4832209e986029b9fabdaad57b1eecb856b)
  24 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  25 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  26 (cherry picked from commit 3c5771a43d8f00e53081871027fea891a091ff5e)
  27 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  28 ---
  29  arch/x86/entry/entry_64.S | 11 +++++++----
  30  1 file changed, 7 insertions(+), 4 deletions(-)
  31
  32 diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
  33 index 87be1cd1fa88..4eff3aca54ed 100644
  34 --- a/arch/x86/entry/entry_64.S
  35 +++ b/arch/x86/entry/entry_64.S
  36 @@ -1572,11 +1572,14 @@ end_repeat_nmi:
  37  nmi_swapgs:
  38         SWAPGS_UNSAFE_STACK
  39  nmi_restore:
  40 -       RESTORE_EXTRA_REGS
  41 -       RESTORE_C_REGS
  42 +       POP_EXTRA_REGS
  43 +       POP_C_REGS
  44
  45 -       /* Point RSP at the "iret" frame. */
  46 -       REMOVE_PT_GPREGS_FROM_STACK 6*8
  47 +       /*
  48 +        * Skip orig_ax and the "outermost" frame to point RSP at the "iret"
  49 +        * at the "iret" frame.
  50 +        */
  51 +       addq    $6*8, %rsp
  52
  53         /*
  54          * Clear "NMI executing".  Set DF first so that we can easily
  55 --
  56 2.14.2
  57