On Fri, Oct 21, 2016 at 10:15 AM, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote: > We have reached the era where monitor bandwidths now exceed 31bits in > frequency calculations, though as we stored them in kHz units we are > safe from overflow in the modelines for some time. > > [ 48.723720] UBSAN: Undefined behaviour in ../drivers/gpu/drm/drm_modes.c:325:49 > [ 48.726943] signed integer overflow: > [ 48.728503] 2240 * 1000000 cannot be represented in type 'int' > > Reported-by: Martin Liška <marxin.liska@xxxxxxxxx> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98372 > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Reviewed-by: Alex Deucher <alexander.deucher@xxxxxxx> > --- > drivers/gpu/drm/drm_modes.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c > index 173b7d335834..f64ac86deb84 100644 > --- a/drivers/gpu/drm/drm_modes.c > +++ b/drivers/gpu/drm/drm_modes.c > @@ -165,6 +165,7 @@ struct drm_display_mode *drm_cvt_mode(struct drm_device *dev, int hdisplay, > unsigned int vfieldrate, hperiod; > int hdisplay_rnd, hmargin, vdisplay_rnd, vmargin, vsync; > int interlace; > + u64 tmp; > > /* allocate the drm_display_mode structure. If failure, we will > * return directly > @@ -322,8 +323,11 @@ struct drm_display_mode *drm_cvt_mode(struct drm_device *dev, int hdisplay, > drm_mode->vsync_end = drm_mode->vsync_start + vsync; > } > /* 15/13. Find pixel clock frequency (kHz for xf86) */ > - drm_mode->clock = drm_mode->htotal * HV_FACTOR * 1000 / hperiod; > - drm_mode->clock -= drm_mode->clock % CVT_CLOCK_STEP; > + tmp = drm_mode->htotal; /* perform intermediate calcs in u64 */ > + tmp *= HV_FACTOR * 1000; > + do_div(tmp, hperiod); > + tmp -= drm_mode->clock % CVT_CLOCK_STEP; > + drm_mode->clock = tmp; > /* 18/16. Find actual vertical frame frequency */ > /* ignore - just set the mode flag for interlaced */ > if (interlaced) { > -- > 2.9.3 > > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/dri-devel _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
