From: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
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@xxxxxxxxxxx>
Reviewed-by: Nicolas Pitre <nico@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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"); \
