From: Heiko Carstens 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 Signed-off-by: Martin Schwidefsky --- 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 +#include + +void copy_from_user_overflow(void) +{ + WARN(1, "Buffer overflow detected!\n"); +} +EXPORT_SYMBOL(copy_from_user_overflow); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/