patches/kernel/0086-x86-entry-64-Remove-the-restore_c_regs_and_iret-labe.patch

   1 From befef5ef70f959cd51694298c4370557e5d846cf Mon Sep 17 00:00:00 2001
   2 From: Andy Lutomirski <luto@kernel.org>
   3 Date: Thu, 2 Nov 2017 00:58:58 -0700
   4 Subject: [PATCH 086/241] x86/entry/64: Remove the restore_c_regs_and_iret
   5  label
   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 The only user was the 64-bit opportunistic SYSRET failure path, and
  13 that path didn't really need it.  This change makes the
  14 opportunistic SYSRET code a bit more straightforward and gets rid of
  15 the label.
  16
  17 Signed-off-by: Andy Lutomirski <luto@kernel.org>
  18 Reviewed-by: Borislav Petkov <bp@suse.de>
  19 Cc: Borislav Petkov <bpetkov@suse.de>
  20 Cc: Brian Gerst <brgerst@gmail.com>
  21 Cc: Dave Hansen <dave.hansen@intel.com>
  22 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  23 Cc: Peter Zijlstra <peterz@infradead.org>
  24 Cc: Thomas Gleixner <tglx@linutronix.de>
  25 Link: http://lkml.kernel.org/r/be3006a7ad3326e3458cf1cc55d416252cbe1986.1509609304.git.luto@kernel.org
  26 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  27 (cherry picked from commit 9da78ba6b47b46428cfdfc0851511ab29c869798)
  28 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  29 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  30 (cherry picked from commit 629c8b858cbe72e88e7f44a8f10e1b434ab80721)
  31 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  32 ---
  33  arch/x86/entry/entry_64.S | 5 ++---
  34  1 file changed, 2 insertions(+), 3 deletions(-)
  35
  36 diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
  37 index 34adfe0221d2..fac354ddf056 100644
  38 --- a/arch/x86/entry/entry_64.S
  39 +++ b/arch/x86/entry/entry_64.S
  40 @@ -245,7 +245,6 @@ entry_SYSCALL64_slow_path:
  41         call    do_syscall_64           /* returns with IRQs disabled */
  42
  43  return_from_SYSCALL_64:
  44 -       RESTORE_EXTRA_REGS
  45         TRACE_IRQS_IRETQ                /* we're about to change IF */
  46
  47         /*
  48 @@ -314,6 +313,7 @@ return_from_SYSCALL_64:
  49          */
  50  syscall_return_via_sysret:
  51         /* rcx and r11 are already restored (see code above) */
  52 +       RESTORE_EXTRA_REGS
  53         RESTORE_C_REGS_EXCEPT_RCX_R11
  54         movq    RSP(%rsp), %rsp
  55         UNWIND_HINT_EMPTY
  56 @@ -321,7 +321,7 @@ syscall_return_via_sysret:
  57
  58  opportunistic_sysret_failed:
  59         SWAPGS
  60 -       jmp     restore_c_regs_and_iret
  61 +       jmp     restore_regs_and_iret
  62  END(entry_SYSCALL_64)
  63
  64  ENTRY(stub_ptregs_64)
  65 @@ -638,7 +638,6 @@ retint_kernel:
  66   */
  67  GLOBAL(restore_regs_and_iret)
  68         RESTORE_EXTRA_REGS
  69 -restore_c_regs_and_iret:
  70         RESTORE_C_REGS
  71         REMOVE_PT_GPREGS_FROM_STACK 8
  72         INTERRUPT_RETURN
  73 --
  74 2.14.2
  75