patches/kernel/0148-x86-dumpstack-Handle-stack-overflow-on-all-stacks.patch

   1 From 11739f104753550b4d256207c07a75f667b7aae4 Mon Sep 17 00:00:00 2001
   2 From: Andy Lutomirski <luto@kernel.org>
   3 Date: Mon, 4 Dec 2017 15:07:18 +0100
   4 Subject: [PATCH 148/241] x86/dumpstack: Handle stack overflow on all stacks
   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 We currently special-case stack overflow on the task stack.  We're
  12 going to start putting special stacks in the fixmap with a custom
  13 layout, so they'll have guard pages, too.  Teach the unwinder to be
  14 able to unwind an overflow of any of the stacks.
  15
  16 Signed-off-by: Andy Lutomirski <luto@kernel.org>
  17 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
  18 Reviewed-by: Borislav Petkov <bp@suse.de>
  19 Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
  20 Cc: Borislav Petkov <bp@alien8.de>
  21 Cc: Borislav Petkov <bpetkov@suse.de>
  22 Cc: Brian Gerst <brgerst@gmail.com>
  23 Cc: Dave Hansen <dave.hansen@intel.com>
  24 Cc: Dave Hansen <dave.hansen@linux.intel.com>
  25 Cc: David Laight <David.Laight@aculab.com>
  26 Cc: Denys Vlasenko <dvlasenk@redhat.com>
  27 Cc: Eduardo Valentin <eduval@amazon.com>
  28 Cc: Greg KH <gregkh@linuxfoundation.org>
  29 Cc: H. Peter Anvin <hpa@zytor.com>
  30 Cc: Josh Poimboeuf <jpoimboe@redhat.com>
  31 Cc: Juergen Gross <jgross@suse.com>
  32 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  33 Cc: Peter Zijlstra <peterz@infradead.org>
  34 Cc: Rik van Riel <riel@redhat.com>
  35 Cc: Will Deacon <will.deacon@arm.com>
  36 Cc: aliguori@amazon.com
  37 Cc: daniel.gruss@iaik.tugraz.at
  38 Cc: hughd@google.com
  39 Cc: keescook@google.com
  40 Link: https://lkml.kernel.org/r/20171204150605.802057305@linutronix.de
  41 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  42 (cherry picked from commit 6e60e583426c2f8751c22c2dfe5c207083b4483a)
  43 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  44 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  45 (cherry picked from commit 1ab51120b9a5baaa46979e4ab8ff28916c9cb846)
  46 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  47 ---
  48  arch/x86/kernel/dumpstack.c | 24 ++++++++++++++----------
  49  1 file changed, 14 insertions(+), 10 deletions(-)
  50
  51 diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
  52 index c211cbdff709..0f4b931e1a02 100644
  53 --- a/arch/x86/kernel/dumpstack.c
  54 +++ b/arch/x86/kernel/dumpstack.c
  55 @@ -112,24 +112,28 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
  56          * - task stack
  57          * - interrupt stack
  58          * - HW exception stacks (double fault, nmi, debug, mce)
  59 +        * - SYSENTER stack
  60          *
  61 -        * x86-32 can have up to three stacks:
  62 +        * x86-32 can have up to four stacks:
  63          * - task stack
  64          * - softirq stack
  65          * - hardirq stack
  66 +        * - SYSENTER stack
  67          */
  68         for (regs = NULL; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
  69                 const char *stack_name;
  70
  71 -               /*
  72 -                * If we overflowed the task stack into a guard page, jump back
  73 -                * to the bottom of the usable stack.
  74 -                */
  75 -               if (task_stack_page(task) - (void *)stack < PAGE_SIZE)
  76 -                       stack = task_stack_page(task);
  77 -
  78 -               if (get_stack_info(stack, task, &stack_info, &visit_mask))
  79 -                       break;
  80 +               if (get_stack_info(stack, task, &stack_info, &visit_mask)) {
  81 +                       /*
  82 +                        * We weren't on a valid stack.  It's possible that
  83 +                        * we overflowed a valid stack into a guard page.
  84 +                        * See if the next page up is valid so that we can
  85 +                        * generate some kind of backtrace if this happens.
  86 +                        */
  87 +                       stack = (unsigned long *)PAGE_ALIGN((unsigned long)stack);
  88 +                       if (get_stack_info(stack, task, &stack_info, &visit_mask))
  89 +                               break;
  90 +               }
  91
  92                 stack_name = stack_type_name(stack_info.type);
  93                 if (stack_name)
  94 --
  95 2.14.2
  96