This is a note to let you know that I've just added the patch titled drm/amd/display: fix potential integer overflow when shifting 32 bit variable bl_pwm to the 5.8-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drm-amd-display-fix-potential-integer-overflow-when-.patch and it can be found in the queue-5.8 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 9a9d4af9efe4587c4a9c135c88d70fe13b0360c6 Author: Colin Ian King <colin.king@xxxxxxxxxxxxx> Date: Tue Aug 18 13:09:14 2020 +0100 drm/amd/display: fix potential integer overflow when shifting 32 bit variable bl_pwm [ Upstream commit 1d5503331b12a76266049289747dfd94f1643fde ] 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@xxxxxxxxxxxxx> Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> 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 ebff9b1e312e5..124c081a0f2ca 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 @@ -75,7 +75,7 @@ static unsigned int calculate_16_bit_backlight_from_pwm(struct dce_panel_cntl *d 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;