[PATCH] Kconfig: Make config Filter access to /dev/mem default y

[wzt.wzt@gmail.com]

Recently, most company start use >=2.6.31 kernels to replace redhat kernels.
But the config "Filter access to /dev/mem" is "default n", that allows kernel
rootkit using /dev/mem again. it could access all kernel memory default. Most 
administrator don't known the "Filter access to /dev/mem" is "defult N", when
he compiles the kernel, it's easily to be attacked by rootkit.

Signed-off-by: Zhitong Wang <zhitong.wangzt@alibaba-inc.com> 

---
 arch/x86/Kconfig.debug            |    3 ++-
 arch/x86/configs/i386_defconfig   |    2 +-
 arch/x86/configs/x86_64_defconfig |    2 +-
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index bc01e3e..733aea6 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -7,6 +7,7 @@ source "lib/Kconfig.debug"
 
 config STRICT_DEVMEM
 	bool "Filter access to /dev/mem"
+	default y
 	---help---
 	  If this option is disabled, you allow userspace (root) access to all
 	  of memory, including kernel and userspace memory. Accidental
@@ -20,7 +21,7 @@ config STRICT_DEVMEM
 	  This is sufficient for dosemu and X and all common users of
 	  /dev/mem.
 
-	  If in doubt, say Y.
+	  If in doubt, say N.
 
 config X86_VERBOSE_BOOTUP
 	bool "Enable verbose x86 bootup info messages"
diff --git a/arch/x86/configs/i386_defconfig b/arch/x86/configs/i386_defconfig
index d28fad1..95c85a8 100644
--- a/arch/x86/configs/i386_defconfig
+++ b/arch/x86/configs/i386_defconfig
@@ -2386,7 +2386,7 @@ CONFIG_PROVIDE_OHCI1394_DMA_INIT=y
 # CONFIG_SAMPLES is not set
 CONFIG_HAVE_ARCH_KGDB=y
 # CONFIG_KGDB is not set
-# CONFIG_STRICT_DEVMEM is not set
+CONFIG_STRICT_DEVMEM=y
 CONFIG_X86_VERBOSE_BOOTUP=y
 CONFIG_EARLY_PRINTK=y
 CONFIG_EARLY_PRINTK_DBGP=y
diff --git a/arch/x86/configs/x86_64_defconfig b/arch/x86/configs/x86_64_defconfig
index 6c86acd..659bfe7 100644
--- a/arch/x86/configs/x86_64_defconfig
+++ b/arch/x86/configs/x86_64_defconfig
@@ -2360,7 +2360,7 @@ CONFIG_PROVIDE_OHCI1394_DMA_INIT=y
 # CONFIG_SAMPLES is not set
 CONFIG_HAVE_ARCH_KGDB=y
 # CONFIG_KGDB is not set
-# CONFIG_STRICT_DEVMEM is not set
+CONFIG_STRICT_DEVMEM=y
 CONFIG_X86_VERBOSE_BOOTUP=y
 CONFIG_EARLY_PRINTK=y
 CONFIG_EARLY_PRINTK_DBGP=y
-- 
1.6.5.3