> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of Alex
> Deucher
> Sent: Tuesday, January 28, 2020 4:06 AM
> To: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx>
> Cc: Allen Chen <allen.chen@xxxxxxxxxx>; Intel Graphics Development <intel-
> gfx@xxxxxxxxxxxxxxxxxxxxx>; Maling list - DRI developers <dri-
> devel@xxxxxxxxxxxxxxxxxxxxx>
> Subject: Re: [Intel-gfx] [PATCH 2/8] drm/edid: Don't accept any old garbage as a
> display descriptor
>
> On Fri, Jan 24, 2020 at 3:02 PM Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx> wrote:
> >
> > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> >
> > Currently we assume any 18 byte descriptor to be a display descritor
> > if only the tag byte matches the expected value. But for detailed
> > timing descriptors that same byte is just the lower 8 bits of hblank,
> > and as such can match any display descriptor tag. To properly validate
> > that the 18 byte descriptor is in fact a display descriptor we must
> > also examine bytes 0-2 (just byte 1 should actually suffice but the
> > spec does say that bytes 0 and
> > 2 must also always be zero for display descriptors so we check those
> > too).
> >
> > Unlike Allen's original proposed patch to just fix is_rb() we roll
> > this out across the board to fix everything.
> >
> > Cc: Allen Chen <allen.chen@xxxxxxxxxx>
> > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> Acked-by: Alex Deucher <alexander.deucher@xxxxxxx>
Looks Good to me.
Reviewed-by: Uma Shankar <uma.shankar@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/drm_edid.c | 65
> > ++++++++++++++++++++++++--------------
> > 1 file changed, 41 insertions(+), 24 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> > index 1b6e544cf5c7..96ae1fde4ce2 100644
> > --- a/drivers/gpu/drm/drm_edid.c
> > +++ b/drivers/gpu/drm/drm_edid.c
> > @@ -2196,6 +2196,12 @@ struct drm_display_mode
> > *drm_mode_find_dmt(struct drm_device *dev, }
> > EXPORT_SYMBOL(drm_mode_find_dmt);
> >
> > +static bool is_display_descriptor(const u8 d[18], u8 tag) {
> > + return d[0] == 0x00 && d[1] == 0x00 &&
> > + d[2] == 0x00 && d[3] == tag; }
> > +
> > typedef void detailed_cb(struct detailed_timing *timing, void
> > *closure);
> >
> > static void
> > @@ -2257,9 +2263,12 @@ static void
> > is_rb(struct detailed_timing *t, void *data) {
> > u8 *r = (u8 *)t;
> > - if (r[3] == EDID_DETAIL_MONITOR_RANGE)
> > - if (r[15] & 0x10)
> > - *(bool *)data = true;
> > +
> > + if (!is_display_descriptor(r, EDID_DETAIL_MONITOR_RANGE))
> > + return;
> > +
> > + if (r[15] & 0x10)
> > + *(bool *)data = true;
> > }
> >
> > /* EDID 1.4 defines this explicitly. For EDID 1.3, we guess, badly.
> > */ @@ -2279,7 +2288,11 @@ static void find_gtf2(struct
> > detailed_timing *t, void *data) {
> > u8 *r = (u8 *)t;
> > - if (r[3] == EDID_DETAIL_MONITOR_RANGE && r[10] == 0x02)
> > +
> > + if (!is_display_descriptor(r, EDID_DETAIL_MONITOR_RANGE))
> > + return;
> > +
> > + if (r[10] == 0x02)
> > *(u8 **)data = r;
> > }
> >
> > @@ -2818,7 +2831,7 @@ do_inferred_modes(struct detailed_timing *timing, void
> *c)
> > struct detailed_non_pixel *data = &timing->data.other_data;
> > struct detailed_data_monitor_range *range = &data->data.range;
> >
> > - if (data->type != EDID_DETAIL_MONITOR_RANGE)
> > + if (!is_display_descriptor((const u8 *)timing,
> > + EDID_DETAIL_MONITOR_RANGE))
> > return;
> >
> > closure->modes += drm_dmt_modes_for_range(closure->connector,
> > @@ -2897,10 +2910,11 @@ static void
> > do_established_modes(struct detailed_timing *timing, void *c) {
> > struct detailed_mode_closure *closure = c;
> > - struct detailed_non_pixel *data = &timing->data.other_data;
> >
> > - if (data->type == EDID_DETAIL_EST_TIMINGS)
> > - closure->modes += drm_est3_modes(closure->connector, timing);
> > + if (!is_display_descriptor((const u8 *)timing, EDID_DETAIL_EST_TIMINGS))
> > + return;
> > +
> > + closure->modes += drm_est3_modes(closure->connector, timing);
> > }
> >
> > /**
> > @@ -2949,19 +2963,19 @@ do_standard_modes(struct detailed_timing *timing,
> void *c)
> > struct detailed_non_pixel *data = &timing->data.other_data;
> > struct drm_connector *connector = closure->connector;
> > struct edid *edid = closure->edid;
> > + int i;
> >
> > - if (data->type == EDID_DETAIL_STD_MODES) {
> > - int i;
> > - for (i = 0; i < 6; i++) {
> > - struct std_timing *std;
> > - struct drm_display_mode *newmode;
> > + if (!is_display_descriptor((const u8 *)timing, EDID_DETAIL_STD_MODES))
> > + return;
> >
> > - std = &data->data.timings[i];
> > - newmode = drm_mode_std(connector, edid, std);
> > - if (newmode) {
> > - drm_mode_probed_add(connector, newmode);
> > - closure->modes++;
> > - }
> > + for (i = 0; i < 6; i++) {
> > + struct std_timing *std = &data->data.timings[i];
> > + struct drm_display_mode *newmode;
> > +
> > + newmode = drm_mode_std(connector, edid, std);
> > + if (newmode) {
> > + drm_mode_probed_add(connector, newmode);
> > + closure->modes++;
> > }
> > }
> > }
> > @@ -3056,10 +3070,11 @@ static void
> > do_cvt_mode(struct detailed_timing *timing, void *c) {
> > struct detailed_mode_closure *closure = c;
> > - struct detailed_non_pixel *data = &timing->data.other_data;
> >
> > - if (data->type == EDID_DETAIL_CVT_3BYTE)
> > - closure->modes += drm_cvt_modes(closure->connector, timing);
> > + if (!is_display_descriptor((const u8 *)timing, EDID_DETAIL_CVT_3BYTE))
> > + return;
> > +
> > + closure->modes += drm_cvt_modes(closure->connector, timing);
> > }
> >
> > static int
> > @@ -4285,8 +4300,10 @@ drm_parse_hdmi_vsdb_audio(struct drm_connector
> > *connector, const u8 *db) static void monitor_name(struct
> > detailed_timing *t, void *data) {
> > - if (t->data.other_data.type == EDID_DETAIL_MONITOR_NAME)
> > - *(u8 **)data = t->data.other_data.data.str.str;
> > + if (!is_display_descriptor((const u8 *)t, EDID_DETAIL_MONITOR_NAME))
> > + return;
> > +
> > + *(u8 **)data = t->data.other_data.data.str.str;
> > }
> >
> > static int get_monitor_name(struct edid *edid, char name[13])
> > --
> > 2.24.1
> >
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> > dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
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