| From ad289b649da0645bc2ee3340b33bae86b5fb87e6 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Tue, 15 Sep 2020 17:20:49 +0100 |
| Subject: drm/rockchip: cdn-dp: fix sign extension on an int multiply for a u64 |
| result |
| |
| From: Colin Ian King <colin.king@canonical.com> |
| |
| [ Upstream commit ce0cb93a5adb283f577cd4661f511047b5e39028 ] |
| |
| The variable bit_per_pix is a u8 and is promoted in the multiplication |
| to an int type and then sign extended to a u64. If the result of the |
| int multiplication is greater than 0x7fffffff then the upper 32 bits will |
| be set to 1 as a result of the sign extension. Avoid this by casting |
| tu_size_reg to u64 to avoid sign extension and also a potential overflow. |
| |
| Fixes: 1a0f7ed3abe2 ("drm/rockchip: cdn-dp: add cdn DP support for rk3399") |
| Signed-off-by: Colin Ian King <colin.king@canonical.com> |
| Reviewed-by: Guenter Roeck <groeck@chromium.org> |
| Signed-off-by: Heiko Stuebner <heiko@sntech.de> |
| Link: https://patchwork.freedesktop.org/patch/msgid/20200915162049.36434-1-colin.king@canonical.com |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/gpu/drm/rockchip/cdn-dp-reg.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| diff --git a/drivers/gpu/drm/rockchip/cdn-dp-reg.c b/drivers/gpu/drm/rockchip/cdn-dp-reg.c |
| index 9d2163ef4d6e..33fb4d05c506 100644 |
| --- a/drivers/gpu/drm/rockchip/cdn-dp-reg.c |
| +++ b/drivers/gpu/drm/rockchip/cdn-dp-reg.c |
| @@ -658,7 +658,7 @@ int cdn_dp_config_video(struct cdn_dp_device *dp) |
| */ |
| do { |
| tu_size_reg += 2; |
| - symbol = tu_size_reg * mode->clock * bit_per_pix; |
| + symbol = (u64)tu_size_reg * mode->clock * bit_per_pix; |
| do_div(symbol, dp->max_lanes * link_rate * 8); |
| rem = do_div(symbol, 1000); |
| if (tu_size_reg > 64) { |
| -- |
| 2.30.2 |
| |
