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ARM: 8051/1: put_user: fix possible data corruption in put_user

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According to arm procedure call standart r2 register is call-cloberred.
So after the result of x expression was put into r2 any following
function call in p may overwrite r2. To fix this, the result of p
expression must be saved to the temporary variable before the
assigment x expression to __r2.

Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Cc: stable@vger.kernel.org
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Andrey Ryabinin 2014-05-07 08:07:25 +01:00 committed by Russell King
parent f9ff907b0a
commit 537094b64b
1 changed files with 2 additions and 1 deletions
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3
arch/arm/include/asm/uaccess.h
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@ -171,8 +171,9 @@ extern int __put_user_8(void *, unsigned long long);
#define __put_user_check(x,p) \
({ \
unsigned long __limit = current_thread_info()->addr_limit - 1; \
const typeof(*(p)) __user *__tmp_p = (p); \
register const typeof(*(p)) __r2 asm("r2") = (x); \
register const typeof(*(p)) __user *__p asm("r0") = (p);\
register const typeof(*(p)) __user *__p asm("r0") = __tmp_p; \
register unsigned long __l asm("r1") = __limit; \
register int __e asm("r0"); \
switch (sizeof(*(__p))) { \