[PATCH][next] drm/amd/display: fix potential integer overflow when shifting 32 bit variable bl_pwm - dri-devel - freedesktop.org experimental mailing list

18 Aug 2020

From: Colin Ian King colin.king@canonical.com
The 32 bit unsigned integer bl_pwm is being shifted using 32 bit arithmetic
and then being assigned to a 64 bit unsigned integer.  There is a potential
for a 32 bit overflow so cast bl_pwm to enforce a 64 bit shift operation
to avoid this.
Addresses-Coverity: ("unintentional integer overflow")
Fixes: 3ba01817365c ("drm/amd/display: Move panel_cntl specific register from abm to panel_cntl.")
Signed-off-by: Colin Ian King colin.king@canonical.com
---
 drivers/gpu/drm/amd/display/dc/dce/dce_panel_cntl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_panel_cntl.c b/drivers/gpu/drm/amd/display/dc/dce/dce_panel_cntl.c
index a6d73d30837c..df7f826eebd8 100644
--- a/drivers/gpu/drm/amd/display/dc/dce/dce_panel_cntl.c
+++ b/drivers/gpu/drm/amd/display/dc/dce/dce_panel_cntl.c
@@ -76,7 +76,7 @@ static unsigned int dce_get_16_bit_backlight_from_pwm(struct panel_cntl *panel_c
    else
    	bl_pwm &= 0xFFFF;
-	current_backlight = bl_pwm << (1 + bl_int_count);
+	current_backlight = (uint64_t)bl_pwm << (1 + bl_int_count);
if (bl_period == 0)
    	bl_period = 0xFFFF;
-- 
2.27.0


    