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);
