[S390] uaccess: implement strict user copy checks

source "lib/Kconfig.debug"

config DEBUG_STRICT_USER_COPY_CHECKS

	bool "Strict user copy size checks"

	---help---

	  Enabling this option turns a certain set of sanity checks for user

	  copy operations into compile time warnings.

	  The copy_from_user() etc checks are there to help test if there

	  are sufficient security checks on the length argument of

	  the copy operation, by having gcc prove that the argument is

	  within bounds.

	  If unsure, or if you run an older (pre 4.4) gcc, say N.

endmenu

		return uaccess.copy_from_user(n, from, to);

}

extern void copy_from_user_overflow(void)

#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS

__compiletime_warning("copy_from_user() buffer size is not provably correct")

#endif

;

/**

 * copy_from_user: - Copy a block of data from user space.

 * @to:   Destination address, in kernel space.

static inline unsigned long __must_check

copy_from_user(void *to, const void __user *from, unsigned long n)

{

	unsigned int sz = __compiletime_object_size(to);

	might_fault();

	if (unlikely(sz != -1 && sz < n)) {

		copy_from_user_overflow();

		return n;

	}

	if (access_ok(VERIFY_READ, from, n))

		n = __copy_from_user(to, from, n);

	else

# Makefile for s390-specific library files..

#

lib-y += delay.o string.o uaccess_std.o uaccess_pt.o

lib-y += delay.o string.o uaccess_std.o uaccess_pt.o usercopy.o

obj-$(CONFIG_32BIT) += div64.o qrnnd.o ucmpdi2.o

lib-$(CONFIG_64BIT) += uaccess_mvcos.o

lib-$(CONFIG_SMP) += spinlock.o

#include <linux/module.h>

#include <linux/bug.h>

void copy_from_user_overflow(void)

{

	WARN(1, "Buffer overflow detected!\n");

}

EXPORT_SYMBOL(copy_from_user_overflow);