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-rw-r--r--lib/Kconfig.debug18
-rw-r--r--lib/Makefile1
-rw-r--r--lib/usercopy.c9
3 files changed, 28 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 77ebaa3dfa12..770a422a42e8 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1292,6 +1292,24 @@ config LATENCYTOP
Enable this option if you want to use the LatencyTOP tool
to find out which userspace is blocking on what kernel operations.
+config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
+ bool
+
+config DEBUG_STRICT_USER_COPY_CHECKS
+ bool "Strict user copy size checks"
+ depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
+ depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
+ 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, say N.
+
source mm/Kconfig.debug
source kernel/trace/Kconfig
diff --git a/lib/Makefile b/lib/Makefile
index 23c9a0fe74fc..e9c52e1b853a 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -15,6 +15,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
is_single_threaded.o plist.o decompress.o kobject_uevent.o \
earlycpio.o
+obj-$(CONFIG_ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS) += usercopy.o
lib-$(CONFIG_MMU) += ioremap.o
lib-$(CONFIG_SMP) += cpumask.o
diff --git a/lib/usercopy.c b/lib/usercopy.c
new file mode 100644
index 000000000000..4f5b1ddbcd25
--- /dev/null
+++ b/lib/usercopy.c
@@ -0,0 +1,9 @@
+#include <linux/export.h>
+#include <linux/bug.h>
+#include <linux/uaccess.h>
+
+void copy_from_user_overflow(void)
+{
+ WARN(1, "Buffer overflow detected!\n");
+}
+EXPORT_SYMBOL(copy_from_user_overflow);