patches/kernel/0091-x86-entry-64-Use-pop-instead-of-movq-in-syscall_retu.patch

   1 From d4b1f2361974bfffa04a528fb2ad393a55d13841 Mon Sep 17 00:00:00 2001
   2 From: Andy Lutomirski <luto@kernel.org>
   3 Date: Thu, 2 Nov 2017 00:59:03 -0700
   4 Subject: [PATCH 091/241] x86/entry/64: Use pop instead of movq in
   5  syscall_return_via_sysret
   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 Saves 64 bytes.
  13
  14 Signed-off-by: Andy Lutomirski <luto@kernel.org>
  15 Reviewed-by: Borislav Petkov <bp@suse.de>
  16 Cc: Borislav Petkov <bpetkov@suse.de>
  17 Cc: Brian Gerst <brgerst@gmail.com>
  18 Cc: Dave Hansen <dave.hansen@intel.com>
  19 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  20 Cc: Peter Zijlstra <peterz@infradead.org>
  21 Cc: Thomas Gleixner <tglx@linutronix.de>
  22 Link: http://lkml.kernel.org/r/6609b7f74ab31c36604ad746e019ea8495aec76c.1509609304.git.luto@kernel.org
  23 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  24 (cherry picked from commit 4fbb39108f972437c44e5ffa781b56635d496826)
  25 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  26 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  27 (cherry picked from commit 1e9a9d5ef9f65eeb26eb8f0974dd3e693894baf1)
  28 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  29 ---
  30  arch/x86/entry/entry_64.S | 14 +++++++++++---
  31  1 file changed, 11 insertions(+), 3 deletions(-)
  32
  33 diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
  34 index 6995f7e08aa1..33a416c7df2d 100644
  35 --- a/arch/x86/entry/entry_64.S
  36 +++ b/arch/x86/entry/entry_64.S
  37 @@ -315,10 +315,18 @@ return_from_SYSCALL_64:
  38          */
  39  syscall_return_via_sysret:
  40         /* rcx and r11 are already restored (see code above) */
  41 -       RESTORE_EXTRA_REGS
  42 -       RESTORE_C_REGS_EXCEPT_RCX_R11
  43 -       movq    RSP(%rsp), %rsp
  44         UNWIND_HINT_EMPTY
  45 +       POP_EXTRA_REGS
  46 +       popq    %rsi    /* skip r11 */
  47 +       popq    %r10
  48 +       popq    %r9
  49 +       popq    %r8
  50 +       popq    %rax
  51 +       popq    %rsi    /* skip rcx */
  52 +       popq    %rdx
  53 +       popq    %rsi
  54 +       popq    %rdi
  55 +       movq    RSP-ORIG_RAX(%rsp), %rsp
  56         USERGS_SYSRET64
  57  END(entry_SYSCALL_64)
  58
  59 --
  60 2.14.2
  61