* [PATCH][next] drm/amd/display: fix potential integer overflow when shifting 32 bit variable bl_pwm
@ 2020-08-18 12:09 Colin King
2020-08-18 14:43 ` Alex Deucher
0 siblings, 1 reply; 2+ messages in thread
From: Colin King @ 2020-08-18 12:09 UTC (permalink / raw)
To: Harry Wentland, Leo Li, Alex Deucher, Christian König,
David Airlie, Daniel Vetter, Anthony Koo, Aurabindo Pillai,
amd-gfx, dri-devel
Cc: kernel-janitors, linux-kernel
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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH][next] drm/amd/display: fix potential integer overflow when shifting 32 bit variable bl_pwm
2020-08-18 12:09 [PATCH][next] drm/amd/display: fix potential integer overflow when shifting 32 bit variable bl_pwm Colin King
@ 2020-08-18 14:43 ` Alex Deucher
0 siblings, 0 replies; 2+ messages in thread
From: Alex Deucher @ 2020-08-18 14:43 UTC (permalink / raw)
To: Colin King
Cc: Harry Wentland, Leo Li, Alex Deucher, Christian König,
David Airlie, Daniel Vetter, Anthony Koo, Aurabindo Pillai,
amd-gfx list, Maling list - DRI developers, kernel-janitors,
LKML
On Tue, Aug 18, 2020 at 8:09 AM Colin King <colin.king@canonical.com> wrote:
>
> 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>
Applied. Thanks!
Alex
> ---
> 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
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
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