ARM: allow kuser helpers to be removed from the vector page
Provide a kernel configuration option to allow the kernel user helpers
to be removed from the vector page, thereby preventing their use with
ROP (return orientated programming) attacks. This option is only
visible for CPU architectures which natively support all the operations
which kernel user helpers would normally provide, and must be enabled
with caution.
Cc: <stable@vger.kernel.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 94caefb..d40d0ef 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -753,6 +753,7 @@
.endr
.endm
+#ifdef CONFIG_KUSER_HELPERS
.align 5
.globl __kuser_helper_start
__kuser_helper_start:
@@ -939,6 +940,8 @@
.globl __kuser_helper_end
__kuser_helper_end:
+#endif
+
THUMB( .thumb )
/*