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Commit 63312b6a authored by Arjan van de Ven's avatar Arjan van de Ven Committed by Ingo Molnar
Browse files

x86: Add a Kconfig option to turn the copy_from_user warnings into errors 



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: default avatarArjan van de Ven <arjan@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <20091002075050.4e9f7641@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 4a312769

arch/x86/Kconfig.debug

+14 −0
Original line number Diff line number Diff line
@@ -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

arch/x86/include/asm/uaccess_32.h

+3 −1
Original line number Diff line number Diff line
@@ -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

;

include/linux/compiler-gcc4.h

+1 −0
Original line number Diff line number Diff line
@@ -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

include/linux/compiler.h

+3 −0
Original line number Diff line number Diff line
@@ -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