[PATCH i-g-t v2] tests/kms_invalid_mode: Attempt divide-by-zero in drm_mode_vrefresh()

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

Add a new subtest which attempts to invoke a div-by-zero via
an overflow in drm_mode_vrefresh() (found by syzbot).

v2: Fix the docs

Link: https://syzkaller.appspot.com/bug?extid=622bba18029bcde672e1
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 tests/kms_invalid_mode.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/tests/kms_invalid_mode.c b/tests/kms_invalid_mode.c
index 4fd644594ef9..1ebce4df3616 100644
--- a/tests/kms_invalid_mode.c
+++ b/tests/kms_invalid_mode.c
@@ -56,6 +56,7 @@
  * @zero-clock:       Clock as zero
  * @zero-hdisplay:    hdisplay as zero
  * @zero-vdisplay:    vdisplay as zero
+ * @overflow-vrefresh: vrefresh calculation overflow
  */
 
 IGT_TEST_DESCRIPTION("Make sure all modesets are rejected when the requested mode is invalid");
@@ -210,6 +211,20 @@ adjust_mode_bad_vtotal(data_t *data, drmModeModeInfoPtr mode)
 	return true;
 }
 
+static bool
+adjust_mode_overflow_vrefresh(data_t *data, drmModeModeInfoPtr mode)
+{
+	/*
+	 * htotal * vtotal * vscan == 2^32
+	 * overflow during vrefresh calculation
+	 */
+	mode->htotal = 32768;
+	mode->vtotal = 32768;
+	mode->vscan = 4;
+
+	return true;
+}
+
 static void
 test_output(data_t *data)
 {
@@ -285,6 +300,9 @@ static const struct {
 	{ .name = "bad-vtotal",
 	  .adjust_mode = adjust_mode_bad_vtotal,
 	},
+	{ .name = "overflow-vrefresh",
+	  .adjust_mode = adjust_mode_overflow_vrefresh,
+	},
 };
 
 static data_t data;
-- 
2.45.2