patches/kernel/0103-x86-entry-32-Fix-cpu_current_top_of_stack-initializa.patch

   1 From 870277eb767ecec9293c5dd5ba5bf1c912251e85 Mon Sep 17 00:00:00 2001
   2 From: Andy Lutomirski <luto@kernel.org>
   3 Date: Thu, 2 Nov 2017 00:59:15 -0700
   4 Subject: [PATCH 103/233] x86/entry/32: Fix cpu_current_top_of_stack
   5  initialization at boot
   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 cpu_current_top_of_stack's initialization forgot about
  13 TOP_OF_KERNEL_STACK_PADDING.  This bug didn't matter because the
  14 idle threads never enter user mode.
  15
  16 Signed-off-by: Andy Lutomirski <luto@kernel.org>
  17 Reviewed-by: Borislav Petkov <bp@suse.de>
  18 Cc: Borislav Petkov <bpetkov@suse.de>
  19 Cc: Brian Gerst <brgerst@gmail.com>
  20 Cc: Dave Hansen <dave.hansen@intel.com>
  21 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  22 Cc: Peter Zijlstra <peterz@infradead.org>
  23 Cc: Thomas Gleixner <tglx@linutronix.de>
  24 Link: http://lkml.kernel.org/r/e5e370a7e6e4fddd1c4e4cf619765d96bb874b21.1509609304.git.luto@kernel.org
  25 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  26 (cherry picked from commit cd493a6deb8b78eca280d05f7fa73fd69403ae29)
  27 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  28 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  29 (cherry picked from commit 258c98e7d4b8f1459772e656cd736c028a13add9)
  30 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  31 ---
  32  arch/x86/kernel/smpboot.c | 3 +--
  33  1 file changed, 1 insertion(+), 2 deletions(-)
  34
  35 diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
  36 index d05006f6c31c..8ea3b18cbdc1 100644
  37 --- a/arch/x86/kernel/smpboot.c
  38 +++ b/arch/x86/kernel/smpboot.c
  39 @@ -961,8 +961,7 @@ void common_cpu_up(unsigned int cpu, struct task_struct *idle)
  40  #ifdef CONFIG_X86_32
  41         /* Stack for startup_32 can be just as for start_secondary onwards */
  42         irq_ctx_init(cpu);
  43 -       per_cpu(cpu_current_top_of_stack, cpu) =
  44 -               (unsigned long)task_stack_page(idle) + THREAD_SIZE;
  45 +       per_cpu(cpu_current_top_of_stack, cpu) = task_top_of_stack(idle);
  46  #else
  47         initial_gs = per_cpu_offset(cpu);
  48  #endif
  49 --
  50 2.14.2
  51