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 5.9-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-5.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 82a7d2f600d4ca274913a87d41cd89547425a176
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 43781e77be431..f9456ff6845b6 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;
