releases/3.14.7/arm-8051-1-put_user-fix-possible-data-corruption-in-put_user.patch

   1 From 537094b64b229bf3ad146042f83e74cf6abe59df Mon Sep 17 00:00:00 2001
   2 From: Andrey Ryabinin <a.ryabinin@samsung.com>
   3 Date: Wed, 7 May 2014 08:07:25 +0100
   4 Subject: ARM: 8051/1: put_user: fix possible data corruption in put_user
   5
   6 From: Andrey Ryabinin <a.ryabinin@samsung.com>
   7
   8 commit 537094b64b229bf3ad146042f83e74cf6abe59df upstream.
   9
  10 According to arm procedure call standart r2 register is call-cloberred.
  11 So after the result of x expression was put into r2 any following
  12 function call in p may overwrite r2. To fix this, the result of p
  13 expression must be saved to the temporary variable before the
  14 assigment x expression to __r2.
  15
  16 Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
  17 Reviewed-by: Nicolas Pitre <nico@linaro.org>
  18 Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
  19 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  20
  21 ---
  22  arch/arm/include/asm/uaccess.h |    3 ++-
  23  1 file changed, 2 insertions(+), 1 deletion(-)
  24
  25 --- a/arch/arm/include/asm/uaccess.h
  26 +++ b/arch/arm/include/asm/uaccess.h
  27 @@ -171,8 +171,9 @@ extern int __put_user_8(void *, unsigned
  28  #define __put_user_check(x,p)                                                  \
  29         ({                                                              \
  30                 unsigned long __limit = current_thread_info()->addr_limit - 1; \
  31 +               const typeof(*(p)) __user *__tmp_p = (p);               \
  32                 register const typeof(*(p)) __r2 asm("r2") = (x);       \
  33 -               register const typeof(*(p)) __user *__p asm("r0") = (p);\
  34 +               register const typeof(*(p)) __user *__p asm("r0") = __tmp_p; \
  35                 register unsigned long __l asm("r1") = __limit;         \
  36                 register int __e asm("r0");                             \
  37                 switch (sizeof(*(__p))) {                               \