releases/5.0.15/linux-kernel.h-use-parentheses-around-argument-in-u6.patch

   1 From e231ad027fd94ba4595f06b00c284a621c2a4e6d Mon Sep 17 00:00:00 2001
   2 From: Jann Horn <jannh@google.com>
   3 Date: Fri, 29 Mar 2019 22:46:49 +0100
   4 Subject: linux/kernel.h: Use parentheses around argument in u64_to_user_ptr()
   5
   6 [ Upstream commit a0fe2c6479aab5723239b315ef1b552673f434a3 ]
   7
   8 Use parentheses around uses of the argument in u64_to_user_ptr() to
   9 ensure that the cast doesn't apply to part of the argument.
  10
  11 There are existing uses of the macro of the form
  12
  13   u64_to_user_ptr(A + B)
  14
  15 which expands to
  16
  17   (void __user *)(uintptr_t)A + B
  18
  19 (the cast applies to the first operand of the addition, the addition
  20 is a pointer addition). This happens to still work as intended, the
  21 semantic difference doesn't cause a difference in behavior.
  22
  23 But I want to use u64_to_user_ptr() with a ternary operator in the
  24 argument, like so:
  25
  26   u64_to_user_ptr(A ? B : C)
  27
  28 This currently doesn't work as intended.
  29
  30 Signed-off-by: Jann Horn <jannh@google.com>
  31 Signed-off-by: Borislav Petkov <bp@suse.de>
  32 Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
  33 Cc: Andrei Vagin <avagin@openvz.org>
  34 Cc: Andrew Morton <akpm@linux-foundation.org>
  35 Cc: Dan Carpenter <dan.carpenter@oracle.com>
  36 Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  37 Cc: "H. Peter Anvin" <hpa@zytor.com>
  38 Cc: Ingo Molnar <mingo@kernel.org>
  39 Cc: Jani Nikula <jani.nikula@intel.com>
  40 Cc: Kees Cook <keescook@chromium.org>
  41 Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
  42 Cc: NeilBrown <neilb@suse.com>
  43 Cc: Peter Zijlstra <peterz@infradead.org>
  44 Cc: Qiaowei Ren <qiaowei.ren@intel.com>
  45 Cc: Thomas Gleixner <tglx@linutronix.de>
  46 Cc: x86-ml <x86@kernel.org>
  47 Link: https://lkml.kernel.org/r/20190329214652.258477-1-jannh@google.com
  48 Signed-off-by: Sasha Levin <sashal@kernel.org>
  49 ---
  50  include/linux/kernel.h | 4 ++--
  51  1 file changed, 2 insertions(+), 2 deletions(-)
  52
  53 diff --git a/include/linux/kernel.h b/include/linux/kernel.h
  54 index 8f0e68e250a76..fd827b2400596 100644
  55 --- a/include/linux/kernel.h
  56 +++ b/include/linux/kernel.h
  57 @@ -73,8 +73,8 @@
  58
  59  #define u64_to_user_ptr(x) (           \
  60  {                                      \
  61 -       typecheck(u64, x);              \
  62 -       (void __user *)(uintptr_t)x;    \
  63 +       typecheck(u64, (x));            \
  64 +       (void __user *)(uintptr_t)(x);  \
  65  }                                      \
  66  )
  67
  68 --
  69 2.20.1
  70