drm/vc4: hdmi: Fixed possible integer overflow

fsaud · mripard · commit 5f940e528da6 · 2022-06-22T09:30:17.000+02:00
Multiplying ints and saving it in unsigned long long could lead to integer overflow before being type casted to unsigned long long. Addresses-Coverity: 1505113: Unintentional integer overflow. Signed-off-by: Saud Farooqui <farooqui_saud@hotmail.com> Signed-off-by: Maxime Ripard <maxime@cerno.tech> Link: https://patchwork.freedesktop.org/patch/msgid/PA4P189MB1421E63C0FF3EBF234A80AB38BA79@PA4P189MB1421.EURP189.PROD.OUTLOOK.COM
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -1481,7 +1481,7 @@ vc4_hdmi_encoder_compute_mode_clock(const struct drm_display_mode *mode,
 				    unsigned int bpc,
 				    enum vc4_hdmi_output_format fmt)
 {
-	unsigned long long clock = mode->clock * 1000;
+	unsigned long long clock = mode->clock * 1000ULL;
 
 	if (mode->flags & DRM_MODE_FLAG_DBLCLK)
 		clock = clock * 2;

Original file line number	Diff line number	Diff line change
`@@ -1481,7 +1481,7 @@ vc4_hdmi_encoder_compute_mode_clock(const struct drm_display_mode *mode,`
`1481`	`1481`	`unsigned int bpc,`
`1482`	`1482`	`enum vc4_hdmi_output_format fmt)`
`1483`	`1483`	`{`
`1484`		`- unsigned long long clock = mode->clock * 1000;`
	`1484`	`+ unsigned long long clock = mode->clock * 1000ULL;`
`1485`	`1485`
`1486`	`1486`	`if (mode->flags & DRM_MODE_FLAG_DBLCLK)`
`1487`	`1487`	`clock = clock * 2;`