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

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Commit 537094b64b229bf3ad146042f83e74cf6abe59df upstream.

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>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Andrey Ryabinin 2019-11-08 13:35:05 +01:00 committed by Greg Kroah-Hartman
parent e4cea4d4c5
commit b4fe083f59
1 changed files with 1 additions and 1 deletions
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2
arch/arm/include/asm/uaccess.h
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@ -251,7 +251,7 @@ extern int __put_user_8(void *, unsigned long long);
({ \
unsigned long __limit = current_thread_info()->addr_limit - 1; \
const typeof(*(p)) __user *__tmp_p = (p); \
register typeof(*(p)) __r2 asm("r2") = (x); \
register const typeof(*(p)) __r2 asm("r2") = (x); \
register const typeof(*(p)) __user *__p asm("r0") = __tmp_p; \
register unsigned long __l asm("r1") = __limit; \
register int __e asm("r0"); \