Adding Alex who is now the driver maintainer.
On 13.02.2025 17:57, Nikita Zhandarovich wrote:
> Gentle ping :)
>
> On 1/16/25 16:48, Nikita Zhandarovich wrote:
>> 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@xxxxxxxxxxxxxxx
>> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@xxxxxxxxxx>
>> ---
>> drivers/gpu/drm/tiny/repaper.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/tiny/repaper.c b/drivers/gpu/drm/tiny/repaper.c
>> index 77944eb17b3c..d76c0e8e05f5 100644
>> --- a/drivers/gpu/drm/tiny/repaper.c
>> +++ b/drivers/gpu/drm/tiny/repaper.c
>> @@ -456,7 +456,7 @@ 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);
>> @@ -467,7 +467,7 @@ 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);
>
