lkdtm: Provide more complete coverage for REFCOUNT tests

The existing REFCOUNT_* LKDTM tests were designed only for testing a narrow
portion of CONFIG_REFCOUNT_FULL. This moves the tests to their own file and
expands their testing to poke each boundary condition.

Since the protections (CONFIG_REFCOUNT_FULL and x86-fast) use different
saturation values and reach-zero behavior, those have to be build-time
set so the tests can actually validate things are happening at the
right places.

Notably, the x86-fast protection will fail REFCOUNT_INC_ZERO and
REFCOUNT_ADD_ZERO since those conditions are not checked (only overflow
is critical to protecting refcount_t). CONFIG_REFCOUNT_FULL will warn for
each REFCOUNT_*_NEGATIVE test since it provides zero-pinning behaviors
(which allows it to pass REFCOUNT_INC_ZERO and REFCOUNT_ADD_ZERO).

Signed-off-by: Kees Cook <keescook@chromium.org>

1 files changed, 0 insertions, 83 deletions

diff --git a/drivers/misc/lkdtm_bugs.c b/drivers/misc/lkdtm_bugs.c
index d9028ef50fbe..ef3d06f901fc 100644
--- a/drivers/misc/lkdtm_bugs.c
+++ b/drivers/misc/lkdtm_bugs.c
@@ -6,7 +6,6 @@
  */
 #include "lkdtm.h"
 #include <linux/list.h>
-#include <linux/refcount.h>
 #include <linux/sched.h>
 #include <linux/sched/signal.h>
 #include <linux/uaccess.h>
@@ -137,88 +136,6 @@ void lkdtm_HUNG_TASK(void)
 	schedule();
 }
 
-void lkdtm_REFCOUNT_SATURATE_INC(void)
-{
-	refcount_t over = REFCOUNT_INIT(UINT_MAX - 1);
-
-	pr_info("attempting good refcount decrement\n");
-	refcount_dec(&over);
-	refcount_inc(&over);
-
-	pr_info("attempting bad refcount inc overflow\n");
-	refcount_inc(&over);
-	refcount_inc(&over);
-	if (refcount_read(&over) == UINT_MAX)
-		pr_err("Correctly stayed saturated, but no BUG?!\n");
-	else
-		pr_err("Fail: refcount wrapped\n");
-}
-
-void lkdtm_REFCOUNT_SATURATE_ADD(void)
-{
-	refcount_t over = REFCOUNT_INIT(UINT_MAX - 1);
-
-	pr_info("attempting good refcount decrement\n");
-	refcount_dec(&over);
-	refcount_inc(&over);
-
-	pr_info("attempting bad refcount add overflow\n");
-	refcount_add(2, &over);
-	if (refcount_read(&over) == UINT_MAX)
-		pr_err("Correctly stayed saturated, but no BUG?!\n");
-	else
-		pr_err("Fail: refcount wrapped\n");
-}
-
-void lkdtm_REFCOUNT_ZERO_DEC(void)
-{
-	refcount_t zero = REFCOUNT_INIT(1);
-
-	pr_info("attempting bad refcount decrement to zero\n");
-	refcount_dec(&zero);
-	if (refcount_read(&zero) == 0)
-		pr_err("Stayed at zero, but no BUG?!\n");
-	else
-		pr_err("Fail: refcount went crazy\n");
-}
-
-void lkdtm_REFCOUNT_ZERO_SUB(void)
-{
-	refcount_t zero = REFCOUNT_INIT(1);
-
-	pr_info("attempting bad refcount subtract past zero\n");
-	if (!refcount_sub_and_test(2, &zero))
-		pr_info("wrap attempt was noticed\n");
-	if (refcount_read(&zero) == 1)
-		pr_err("Correctly stayed above 0, but no BUG?!\n");
-	else
-		pr_err("Fail: refcount wrapped\n");
-}
-
-void lkdtm_REFCOUNT_ZERO_INC(void)
-{
-	refcount_t zero = REFCOUNT_INIT(0);
-
-	pr_info("attempting bad refcount increment from zero\n");
-	refcount_inc(&zero);
-	if (refcount_read(&zero) == 0)
-		pr_err("Stayed at zero, but no BUG?!\n");
-	else
-		pr_err("Fail: refcount went past zero\n");
-}
-
-void lkdtm_REFCOUNT_ZERO_ADD(void)
-{
-	refcount_t zero = REFCOUNT_INIT(0);
-
-	pr_info("attempting bad refcount addition from zero\n");
-	refcount_add(2, &zero);
-	if (refcount_read(&zero) == 0)
-		pr_err("Stayed at zero, but no BUG?!\n");
-	else
-		pr_err("Fail: refcount went past zero\n");
-}
-
 void lkdtm_CORRUPT_LIST_ADD(void)
 {
 	/*