drm/edid: fix invalid EDID extension block filtering

[ Upstream commit 3aefc722ff ]

The invalid EDID block filtering uses the number of valid EDID
extensions instead of all EDID extensions for looping the extensions in
the copy. This is fine, by coincidence, if all the invalid blocks are at
the end of the EDID. However, it's completely broken if there are
invalid extensions in the middle; the invalid blocks are included and
valid blocks are excluded.

Fix it by modifying the base block after, not before, the copy.

Fixes: 14544d0937 ("drm/edid: Only print the bad edid when aborting")
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220330170426.349248-1-jani.nikula@intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Jani Nikula 2022-03-30 20:04:26 +03:00 committed by Justin Hammond
parent a991b6d6c7
commit 7989e5daab

View file

@ -1994,9 +1994,6 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
connector_bad_edid(connector, edid, edid[0x7e] + 1);
edid[EDID_LENGTH-1] += edid[0x7e] - valid_extensions;
edid[0x7e] = valid_extensions;
new = kmalloc_array(valid_extensions + 1, EDID_LENGTH,
GFP_KERNEL);
if (!new)
@ -2013,6 +2010,9 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
base += EDID_LENGTH;
}
new[EDID_LENGTH - 1] += new[0x7e] - valid_extensions;
new[0x7e] = valid_extensions;
kfree(edid);
edid = new;
}