From 63312b6a6faae3f2e5577f2b001e3b504f10a2aa Mon Sep 17 00:00:00 2001 From: Arjan van de Ven Date: Fri, 2 Oct 2009 07:50:50 -0700 Subject: [PATCH] x86: Add a Kconfig option to turn the copy_from_user warnings into errors MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit For automated testing it is useful to have the option to turn the warnings on copy_from_user() etc checks into errors: In function ‘copy_from_user’, inlined from ‘fd_copyin’ at drivers/block/floppy.c:3080, inlined from ‘fd_ioctl’ at drivers/block/floppy.c:3503: linux/arch/x86/include/asm/uaccess_32.h:213: error: call to ‘copy_from_user_overflow’ declared with attribute error: copy_from_user buffer size is not provably correct Signed-off-by: Arjan van de Ven Cc: Linus Torvalds Cc: Andrew Morton LKML-Reference: <20091002075050.4e9f7641@infradead.org> Signed-off-by: Ingo Molnar --- arch/x86/Kconfig.debug | 14 ++++++++++++++ arch/x86/include/asm/uaccess_32.h | 4 +++- include/linux/compiler-gcc4.h | 1 + include/linux/compiler.h | 3 +++ 4 files changed, 21 insertions(+), 1 deletion(-) diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug index d105f29bb6bb..1bd2e36f1538 100644 --- a/arch/x86/Kconfig.debug +++ b/arch/x86/Kconfig.debug @@ -287,4 +287,18 @@ config OPTIMIZE_INLINING If unsure, say N. +config DEBUG_STRICT_USER_COPY_CHECKS + bool "Strict copy size checks" + depends on DEBUG_KERNEL + ---help--- + Enabling this option turns a certain set of sanity checks for user + copy operations into compile time failures. + + 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 diff --git a/arch/x86/include/asm/uaccess_32.h b/arch/x86/include/asm/uaccess_32.h index 952f9e793c3e..0c9825e97f36 100644 --- a/arch/x86/include/asm/uaccess_32.h +++ b/arch/x86/include/asm/uaccess_32.h @@ -193,7 +193,9 @@ unsigned long __must_check _copy_from_user(void *to, extern void copy_from_user_overflow(void) -#ifdef CONFIG_DEBUG_STACKOVERFLOW +#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS + __compiletime_error("copy_from_user() buffer size is not provably correct") +#else __compiletime_warning("copy_from_user() buffer size is not provably correct") #endif ; diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h index f1709c1f9eae..77542c57e20a 100644 --- a/include/linux/compiler-gcc4.h +++ b/include/linux/compiler-gcc4.h @@ -41,4 +41,5 @@ #define __compiletime_object_size(obj) __builtin_object_size(obj, 0) #if __GNUC_MINOR__ >= 4 #define __compiletime_warning(message) __attribute__((warning(message))) +#define __compiletime_error(message) __attribute__((error(message))) #endif diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 950356311f12..88fd4b673cb4 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -273,6 +273,9 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); #ifndef __compiletime_warning # define __compiletime_warning(message) #endif +#ifndef __compiletime_error +# define __compiletime_error(message) +#endif /* * Prevent the compiler from merging or refetching accesses. The compiler -- GitLab