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>
> ---
> 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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