patches/kernel/0085-ptrace-x86-Make-user_64bit_mode-available-to-32-bit-.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
   3 Date: Fri, 27 Oct 2017 13:25:30 -0700
   4 Subject: [PATCH] ptrace,x86: Make user_64bit_mode() available to 32-bit builds
   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 In its current form, user_64bit_mode() can only be used when CONFIG_X86_64
  12 is selected. This implies that code built with CONFIG_X86_64=n cannot use
  13 it. If a piece of code needs to be built for both CONFIG_X86_64=y and
  14 CONFIG_X86_64=n and wants to use this function, it needs to wrap it in
  15 an #ifdef/#endif; potentially, in multiple places.
  16
  17 This can be easily avoided with a single #ifdef/#endif pair within
  18 user_64bit_mode() itself.
  19
  20 Suggested-by: Borislav Petkov <bp@suse.de>
  21 Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
  22 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
  23 Reviewed-by: Borislav Petkov <bp@suse.de>
  24 Cc: "Michael S. Tsirkin" <mst@redhat.com>
  25 Cc: Peter Zijlstra <peterz@infradead.org>
  26 Cc: Dave Hansen <dave.hansen@linux.intel.com>
  27 Cc: ricardo.neri@intel.com
  28 Cc: Adrian Hunter <adrian.hunter@intel.com>
  29 Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
  30 Cc: Huang Rui <ray.huang@amd.com>
  31 Cc: Qiaowei Ren <qiaowei.ren@intel.com>
  32 Cc: Shuah Khan <shuah@kernel.org>
  33 Cc: Kees Cook <keescook@chromium.org>
  34 Cc: Jonathan Corbet <corbet@lwn.net>
  35 Cc: Jiri Slaby <jslaby@suse.cz>
  36 Cc: Dmitry Vyukov <dvyukov@google.com>
  37 Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>
  38 Cc: Chris Metcalf <cmetcalf@mellanox.com>
  39 Cc: Brian Gerst <brgerst@gmail.com>
  40 Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
  41 Cc: Andy Lutomirski <luto@kernel.org>
  42 Cc: Colin Ian King <colin.king@canonical.com>
  43 Cc: Chen Yucong <slaoub@gmail.com>
  44 Cc: Adam Buchbinder <adam.buchbinder@gmail.com>
  45 Cc: Vlastimil Babka <vbabka@suse.cz>
  46 Cc: Lorenzo Stoakes <lstoakes@gmail.com>
  47 Cc: Masami Hiramatsu <mhiramat@kernel.org>
  48 Cc: Paolo Bonzini <pbonzini@redhat.com>
  49 Cc: Andrew Morton <akpm@linux-foundation.org>
  50 Cc: Thomas Garnier <thgarnie@google.com>
  51 Link: https://lkml.kernel.org/r/1509135945-13762-4-git-send-email-ricardo.neri-calderon@linux.intel.com
  52
  53 (cherry picked from commit e27c310af5c05cf876d9cad006928076c27f54d4)
  54 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  55 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  56 (cherry picked from commit 20ddf08f867d3d96788299cd2fb7676590d64250)
  57 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  58 ---
  59  arch/x86/include/asm/ptrace.h | 6 +++++-
  60  1 file changed, 5 insertions(+), 1 deletion(-)
  61
  62 diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
  63 index 2b5d686ea9f3..ea78a8438a8a 100644
  64 --- a/arch/x86/include/asm/ptrace.h
  65 +++ b/arch/x86/include/asm/ptrace.h
  66 @@ -115,9 +115,9 @@ static inline int v8086_mode(struct pt_regs *regs)
  67  #endif
  68  }
  69
  70 -#ifdef CONFIG_X86_64
  71  static inline bool user_64bit_mode(struct pt_regs *regs)
  72  {
  73 +#ifdef CONFIG_X86_64
  74  #ifndef CONFIG_PARAVIRT
  75         /*
  76          * On non-paravirt systems, this is the only long mode CPL 3
  77 @@ -128,8 +128,12 @@ static inline bool user_64bit_mode(struct pt_regs *regs)
  78         /* Headers are too twisted for this to go in paravirt.h. */
  79         return regs->cs == __USER_CS || regs->cs == pv_info.extra_user_64bit_cs;
  80  #endif
  81 +#else /* !CONFIG_X86_64 */
  82 +       return false;
  83 +#endif
  84  }
  85
  86 +#ifdef CONFIG_X86_64
  87  #define current_user_stack_pointer()   current_pt_regs()->sp
  88  #define compat_user_stack_pointer()    current_pt_regs()->sp
  89  #endif
  90 --
  91 2.14.2
  92