5 files changed, 57 insertions, 3 deletions

diff --git a/drivers/misc/lkdtm/Makefile b/drivers/misc/lkdtm/Makefile
index fb10eafe9bde..c70b3822013f 100644
--- a/drivers/misc/lkdtm/Makefile
+++ b/drivers/misc/lkdtm/Makefile
@@ -9,6 +9,7 @@ lkdtm-$(CONFIG_LKDTM)		+= refcount.o
 lkdtm-$(CONFIG_LKDTM)		+= rodata_objcopy.o
 lkdtm-$(CONFIG_LKDTM)		+= usercopy.o
 lkdtm-$(CONFIG_LKDTM)		+= stackleak.o
+lkdtm-$(CONFIG_LKDTM)		+= cfi.o
 
 KASAN_SANITIZE_stackleak.o	:= n
 KCOV_INSTRUMENT_rodata.o	:= n
diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c
index 1606658b9b7e..7284a22b1a09 100644
--- a/drivers/misc/lkdtm/bugs.c
+++ b/drivers/misc/lkdtm/bugs.c
@@ -22,7 +22,7 @@ struct lkdtm_list {
  * recurse past the end of THREAD_SIZE by default.
  */
 #if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0)
-#define REC_STACK_SIZE (CONFIG_FRAME_WARN / 2)
+#define REC_STACK_SIZE (_AC(CONFIG_FRAME_WARN, UL) / 2)
 #else
 #define REC_STACK_SIZE (THREAD_SIZE / 8)
 #endif
@@ -75,7 +75,12 @@ static int warn_counter;
 
 void lkdtm_WARNING(void)
 {
-	WARN(1, "Warning message trigger count: %d\n", warn_counter++);
+	WARN_ON(++warn_counter);
+}
+
+void lkdtm_WARNING_MESSAGE(void)
+{
+	WARN(1, "Warning message trigger count: %d\n", ++warn_counter);
 }
 
 void lkdtm_EXCEPTION(void)
@@ -91,7 +96,7 @@ void lkdtm_LOOP(void)
 
 void lkdtm_EXHAUST_STACK(void)
 {
-	pr_info("Calling function with %d frame size to depth %d ...\n",
+	pr_info("Calling function with %lu frame size to depth %d ...\n",
 		REC_STACK_SIZE, recur_count);
 	recursive_loop(recur_count);
 	pr_info("FAIL: survived without exhausting stack?!\n");
diff --git a/drivers/misc/lkdtm/cfi.c b/drivers/misc/lkdtm/cfi.c
new file mode 100644
index 000000000000..e73ebdbfa806
--- /dev/null
+++ b/drivers/misc/lkdtm/cfi.c
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This is for all the tests relating directly to Control Flow Integrity.
+ */
+#include "lkdtm.h"
+
+static int called_count;
+
+/* Function taking one argument, without a return value. */
+static noinline void lkdtm_increment_void(int *counter)
+{
+	(*counter)++;
+}
+
+/* Function taking one argument, returning int. */
+static noinline int lkdtm_increment_int(int *counter)
+{
+	(*counter)++;
+
+	return *counter;
+}
+/*
+ * This tries to call an indirect function with a mismatched prototype.
+ */
+void lkdtm_CFI_FORWARD_PROTO(void)
+{
+	/*
+	 * Matches lkdtm_increment_void()'s prototype, but not
+	 * lkdtm_increment_int()'s prototype.
+	 */
+	void (*func)(int *);
+
+	pr_info("Calling matched prototype ...\n");
+	func = lkdtm_increment_void;
+	func(&called_count);
+
+	pr_info("Calling mismatched prototype ...\n");
+	func = (void *)lkdtm_increment_int;
+	func(&called_count);
+
+	pr_info("Fail: survived mismatched prototype function call!\n");
+}
diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
index 66ae6b2a6950..cbc4c9045a99 100644
--- a/drivers/misc/lkdtm/core.c
+++ b/drivers/misc/lkdtm/core.c
@@ -104,6 +104,7 @@ static const struct crashtype crashtypes[] = {
 	CRASHTYPE(PANIC),
 	CRASHTYPE(BUG),
 	CRASHTYPE(WARNING),
+	CRASHTYPE(WARNING_MESSAGE),
 	CRASHTYPE(EXCEPTION),
 	CRASHTYPE(LOOP),
 	CRASHTYPE(EXHAUST_STACK),
@@ -169,6 +170,7 @@ static const struct crashtype crashtypes[] = {
 	CRASHTYPE(USERCOPY_KERNEL),
 	CRASHTYPE(USERCOPY_KERNEL_DS),
 	CRASHTYPE(STACKLEAK_ERASING),
+	CRASHTYPE(CFI_FORWARD_PROTO),
 };
 
 
diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h
index 6a284a87a037..ab446e0bde97 100644
--- a/drivers/misc/lkdtm/lkdtm.h
+++ b/drivers/misc/lkdtm/lkdtm.h
@@ -11,6 +11,7 @@ void __init lkdtm_bugs_init(int *recur_param);
 void lkdtm_PANIC(void);
 void lkdtm_BUG(void);
 void lkdtm_WARNING(void);
+void lkdtm_WARNING_MESSAGE(void);
 void lkdtm_EXCEPTION(void);
 void lkdtm_LOOP(void);
 void lkdtm_EXHAUST_STACK(void);
@@ -95,4 +96,7 @@ void lkdtm_USERCOPY_KERNEL_DS(void);
 /* lkdtm_stackleak.c */
 void lkdtm_STACKLEAK_ERASING(void);
 
+/* cfi.c */
+void lkdtm_CFI_FORWARD_PROTO(void);
+
 #endif