From: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Same as on x86 and sparc, besides the fact that enabling the option
will just emit compile time warnings instead of errors.
Keeps allyesconfig kernels compiling.
Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
---
arch/s390/Kconfig.debug | 13 +++++++++++++
arch/s390/include/asm/uaccess.h | 12 ++++++++++++
arch/s390/lib/Makefile | 2 +-
arch/s390/lib/usercopy.c | 8 ++++++++
4 files changed, 34 insertions(+), 1 deletion(-)
Index: quilt-2.6/arch/s390/include/asm/uaccess.h
===================================================================
--- quilt-2.6.orig/arch/s390/include/asm/uaccess.h 2010-02-24 09:28:13.000000000 +0100
+++ quilt-2.6/arch/s390/include/asm/uaccess.h 2010-02-24 09:44:22.000000000 +0100
@@ -265,6 +265,12 @@
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.
@@ -284,7 +290,13 @@
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
Index: quilt-2.6/arch/s390/Kconfig.debug
===================================================================
--- quilt-2.6.orig/arch/s390/Kconfig.debug 2010-02-24 09:28:13.000000000 +0100
+++ quilt-2.6/arch/s390/Kconfig.debug 2010-02-24 09:44:22.000000000 +0100
@@ -6,4 +6,17 @@
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
Index: quilt-2.6/arch/s390/lib/Makefile
===================================================================
--- quilt-2.6.orig/arch/s390/lib/Makefile 2010-02-24 09:28:13.000000000 +0100
+++ quilt-2.6/arch/s390/lib/Makefile 2010-02-24 09:44:22.000000000 +0100
@@ -2,7 +2,7 @@
# 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
Index: quilt-2.6/arch/s390/lib/usercopy.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ quilt-2.6/arch/s390/lib/usercopy.c 2010-02-24 09:44:22.000000000 +0100
@@ -0,0 +1,8 @@
+#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);
--
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