patches/kernel/0199-x86-mm-pti-Force-entry-through-trampoline-when-PTI-a.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Thomas Gleixner <tglx@linutronix.de>
   3 Date: Mon, 4 Dec 2017 15:07:43 +0100
   4 Subject: [PATCH] x86/mm/pti: Force entry through trampoline when PTI active
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 CVE-2017-5754
  10
  11 Force the entry through the trampoline only when PTI is active. Otherwise
  12 go through the normal entry code.
  13
  14 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
  15 Reviewed-by: Borislav Petkov <bp@suse.de>
  16 Cc: Andy Lutomirski <luto@kernel.org>
  17 Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
  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: Denys Vlasenko <dvlasenk@redhat.com>
  23 Cc: Eduardo Valentin <eduval@amazon.com>
  24 Cc: Greg KH <gregkh@linuxfoundation.org>
  25 Cc: H. Peter Anvin <hpa@zytor.com>
  26 Cc: Josh Poimboeuf <jpoimboe@redhat.com>
  27 Cc: Juergen Gross <jgross@suse.com>
  28 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  29 Cc: Peter Zijlstra <peterz@infradead.org>
  30 Cc: Will Deacon <will.deacon@arm.com>
  31 Cc: aliguori@amazon.com
  32 Cc: daniel.gruss@iaik.tugraz.at
  33 Cc: hughd@google.com
  34 Cc: keescook@google.com
  35 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  36 (cherry picked from commit 8d4b067895791ab9fdb1aadfc505f64d71239dd2)
  37 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  38 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  39 (cherry picked from commit 9ae1ea4821648be179a96fe65b3ed4bd111a5c98)
  40 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  41 ---
  42  arch/x86/kernel/cpu/common.c | 5 ++++-
  43  1 file changed, 4 insertions(+), 1 deletion(-)
  44
  45 diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
  46 index 623ba3635793..99f37d1636ff 100644
  47 --- a/arch/x86/kernel/cpu/common.c
  48 +++ b/arch/x86/kernel/cpu/common.c
  49 @@ -1340,7 +1340,10 @@ void syscall_init(void)
  50                 (entry_SYSCALL_64_trampoline - _entry_trampoline);
  51
  52         wrmsr(MSR_STAR, 0, (__USER32_CS << 16) | __KERNEL_CS);
  53 -       wrmsrl(MSR_LSTAR, SYSCALL64_entry_trampoline);
  54 +       if (static_cpu_has(X86_FEATURE_PTI))
  55 +               wrmsrl(MSR_LSTAR, SYSCALL64_entry_trampoline);
  56 +       else
  57 +               wrmsrl(MSR_LSTAR, (unsigned long)entry_SYSCALL_64);
  58
  59  #ifdef CONFIG_IA32_EMULATION
  60         wrmsrl(MSR_CSTAR, (unsigned long)entry_SYSCALL_compat);
  61 --
  62 2.14.2
  63