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authorArjan van de Ven <arjan@infradead.org>2009-10-02 07:50:50 -0700
committerIngo Molnar <mingo@elte.hu>2009-10-02 19:01:42 +0200
commit63312b6a6faae3f2e5577f2b001e3b504f10a2aa (patch)
tree5ef6f8449d844652c7046c2659409ef8297f3e0b
parent4a3127693001c61a21d1ce680db6340623f52e93 (diff)
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: Arjan 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: Ingo Molnar <mingo@elte.hu>
-rw-r--r--arch/x86/Kconfig.debug14
-rw-r--r--arch/x86/include/asm/uaccess_32.h4
-rw-r--r--include/linux/compiler-gcc4.h1
-rw-r--r--include/linux/compiler.h3
4 files changed, 21 insertions, 1 deletions
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