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drm/repaper: fix integer overflows in repeat functions

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commit 4d098000ac193f359e6b8ca4801dbdbd6a27b41f upstream.

There are conditions, albeit somewhat unlikely, under which right hand
expressions, calculating the end of time period in functions like
repaper_frame_fixed_repeat(), may overflow.

For instance, if 'factor10x' in repaper_get_temperature() is high
enough (170), as is 'epd->stage_time' in repaper_probe(), then the
resulting value of 'end' will not fit in unsigned int expression.

Mitigate this by casting 'epd->factored_stage_time' to wider type before
any multiplication is done.

Found by Linux Verification Center (linuxtesting.org) with static
analysis tool SVACE.

Fixes: 3589211e9b ("drm/tinydrm: Add RePaper e-ink driver")
Cc: stable@vger.kernel.org
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
Signed-off-by: Alex Lanzano <lanzano.alex@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250116134801.22067-1-n.zhandarovich@fintech.ru
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nikita Zhandarovich
2025-01-16 05:48:01 -08:00
committed by Greg Kroah-Hartman
parent de67afd688
commit b33386fabb
1 changed files with 2 additions and 2 deletions
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4
drivers/gpu/drm/tiny/repaper.c
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@@ -455,7 +455,7 @@ static void repaper_frame_fixed_repeat(struct repaper_epd *epd, u8 fixed_value,
enum repaper_stage stage)
{
u64 start = local_clock();
u64 end = start + (epd->factored_stage_time * 1000 * 1000);
u64 end = start + ((u64)epd->factored_stage_time * 1000 * 1000);
do {
repaper_frame_fixed(epd, fixed_value, stage);
@@ -466,7 +466,7 @@ static void repaper_frame_data_repeat(struct repaper_epd *epd, const u8 *image,
const u8 *mask, enum repaper_stage stage)
{
u64 start = local_clock();
u64 end = start + (epd->factored_stage_time * 1000 * 1000);
u64 end = start + ((u64)epd->factored_stage_time * 1000 * 1000);
do {
repaper_frame_data(epd, image, mask, stage);