From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> We had a bug in i915 land recently where X passed in a zeroed mode with mode_valid=1 to setcrtc. That didn't go down so well and caused a div-by-zero in i915. For a long time I've been thinking that we need some real checks to validate the modes we feed into the hardware. I started to sketch out something for that but it quickly turned into a bit of a nightmare with the whole panel fitter, stereo 3D, SDVO etc. special cases we have in i915. So I gave up on that for now, and instead cooked up this small series to add some basic sanity checks to the mode validation, and also apply the same sanity checks to user provided modes. This is enough to prevent the div-by-zero in i915 with buggy X. The risk is that we start to reject some modes that more or less worked by accident before. Given how lax we've been in handling the panel fitter on i915 for instance, this could be a real problem if people have been useing custom modes that have been filled out only partially. But I'm hoping the number of users doing that is so small that we can risk it. The other concern is drivers which might also provide funky modes from their .get_modes(). I tried to look at all the drivers a bit, and most produce modes via EDID, CVT, DMT, or drm_display_mode_from_videomode(). All of those look safe, except mode->clock might be an issue with drm_display_mode_from_videomode(), but hopefully there's some kind of clock provided in most cases. I didn't dig through all the nooks and crannies in all drivers though, so may have missed something. Ville Syrjälä (3): drm: Reorganize probed mode validation drm: Perform basic sanity checks on probed modes drm: Do basic sanity checks for user modes drivers/gpu/drm/drm_crtc.c | 6 ++++ drivers/gpu/drm/drm_modes.c | 56 ++++++++++++++++++++++++++++++-------- drivers/gpu/drm/drm_probe_helper.c | 43 ++++++++++++++--------------- include/drm/drm_modes.h | 6 ++-- 4 files changed, 74 insertions(+), 37 deletions(-) -- 2.0.4 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
