patches/kernel/0167-x86-vsyscall-64-Warn-and-fail-vsyscall-emulation-in-.patch

   1 From e8354b2be6f97e97515021452082436cec8857ea Mon Sep 17 00:00:00 2001
   2 From: Andy Lutomirski <luto@kernel.org>
   3 Date: Sun, 10 Dec 2017 22:47:20 -0800
   4 Subject: [PATCH 167/233] x86/vsyscall/64: Warn and fail vsyscall emulation in
   5  NATIVE mode
   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 If something goes wrong with pagetable setup, vsyscall=native will
  13 accidentally fall back to emulation.  Make it warn and fail so that we
  14 notice.
  15
  16 Signed-off-by: Andy Lutomirski <luto@kernel.org>
  17 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
  18 Cc: Borislav Petkov <bp@alien8.de>
  19 Cc: Brian Gerst <brgerst@gmail.com>
  20 Cc: Dave Hansen <dave.hansen@linux.intel.com>
  21 Cc: David Laight <David.Laight@aculab.com>
  22 Cc: H. Peter Anvin <hpa@zytor.com>
  23 Cc: Josh Poimboeuf <jpoimboe@redhat.com>
  24 Cc: Juergen Gross <jgross@suse.com>
  25 Cc: Kees Cook <keescook@chromium.org>
  26 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  27 Cc: Peter Zijlstra <peterz@infradead.org>
  28 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  29 (cherry picked from commit 4831b779403a836158917d59a7ca880483c67378)
  30 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  31 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  32 (cherry picked from commit ba10c7488b12c3106d79c8b2ba3f4e79c7e40ee4)
  33 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  34 ---
  35  arch/x86/entry/vsyscall/vsyscall_64.c | 4 ++++
  36  1 file changed, 4 insertions(+)
  37
  38 diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c
  39 index 91f3133cf5f1..5e56a4ced848 100644
  40 --- a/arch/x86/entry/vsyscall/vsyscall_64.c
  41 +++ b/arch/x86/entry/vsyscall/vsyscall_64.c
  42 @@ -138,6 +138,10 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
  43
  44         WARN_ON_ONCE(address != regs->ip);
  45
  46 +       /* This should be unreachable in NATIVE mode. */
  47 +       if (WARN_ON(vsyscall_mode == NATIVE))
  48 +               return false;
  49 +
  50         if (vsyscall_mode == NONE) {
  51                 warn_bad_vsyscall(KERN_INFO, regs,
  52                                   "vsyscall attempted with vsyscall=none");
  53 --
  54 2.14.2
  55