Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 24/75] ARM: 8051/1: put_user: fix possible data corruption in put_user | Date | Fri, 8 Nov 2019 19:49:41 +0100 |
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From: Andrey Ryabinin <a.ryabinin@samsung.com>
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> --- arch/arm/include/asm/uaccess.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -251,7 +251,7 @@ extern int __put_user_8(void *, unsigned ({ \ 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"); \
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