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    Subject[PATCH 5.8 171/633] drm/amd/display: fix potential integer overflow when shifting 32 bit variable bl_pwm
    Date
    From: Colin Ian King <colin.king@canonical.com>

    [ 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@canonical.com>
    Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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 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;
    --
    2.25.1


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