5.4-stable review patch. If anyone has any objections, please let me know.
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From: Nikita Zhandarovich n.zhandarovich@fintech.ru
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: 3589211e9b03 ("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.zhand... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/tiny/repaper.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/gpu/drm/tiny/repaper.c +++ b/drivers/gpu/drm/tiny/repaper.c @@ -454,7 +454,7 @@ static void repaper_frame_fixed_repeat(s 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); @@ -465,7 +465,7 @@ static void repaper_frame_data_repeat(st 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);