| Message ID | 20210929110804.210725-1-colin.king@canonical.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/msm/mdp4: Fix potential integer overflow on 32 bit multiply | expand |
On 29/09/2021 12:08, Colin King wrote: > From: Colin Ian King <colin.king@canonical.com> > > In the case where clock is 2147485 or greater the 32 bit multiplication > by 1000 will cause an integer overflow. Fix this by making the constant > 1000 a long to ensure a long multiply occurs to avoid the overflow > before assigning the result to the long result in variable requested. > Most probably a theoretical overflow issue, but worth fixing. > > Addresses-Coverity: ("Unintentional integer overflow") > Fixes: 3e87599b68e7 ("drm/msm/mdp4: add LVDS panel support") > Signed-off-by: Colin Ian King <colin.king@canonical.com> > --- > drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_connector.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_connector.c b/drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_connector.c > index 7288041dd86a..deada745d5b9 100644 > --- a/drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_connector.c > +++ b/drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_connector.c > @@ -64,7 +64,7 @@ static int mdp4_lvds_connector_mode_valid(struct drm_connector *connector, > struct drm_encoder *encoder = mdp4_lvds_connector->encoder; > long actual, requested; > > - requested = 1000 * mode->clock; > + requested = 1000L * mode->clock; > actual = mdp4_lcdc_round_pixclk(encoder, requested); > > DBG("requested=%ld, actual=%ld", requested, actual); > NACK: there are a few more occurrences of this in the msm driver, I'll fix them up for a V2.
diff --git a/drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_connector.c b/drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_connector.c index 7288041dd86a..deada745d5b9 100644 --- a/drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_connector.c +++ b/drivers/gpu/drm/msm/disp/mdp4/mdp4_lvds_connector.c @@ -64,7 +64,7 @@ static int mdp4_lvds_connector_mode_valid(struct drm_connector *connector, struct drm_encoder *encoder = mdp4_lvds_connector->encoder; long actual, requested; - requested = 1000 * mode->clock; + requested = 1000L * mode->clock; actual = mdp4_lcdc_round_pixclk(encoder, requested); DBG("requested=%ld, actual=%ld", requested, actual);