Commit 8e88c752 authored Mar 13, 2020 by Ville Syrjälä

drm/edid: Don't parse garbage as DispID blocks



Currently the code assumes that the entire EDID extesion block
can be taken up by the DispID blocks. That is not true. There
is at least always the DispID checksum, and potentially fill
bytes if the extension block uses the interior fill scheme
to pad out to fill EDID block size.

So let's not parse the checksum or the fill bytes as DispID
blocks by having drm_find_displayid_extension() return the
actual length of the DispID data to the caller.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200313162054.16009-7-ville.syrjala@linux.intel.com


Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

parent ea0aa608

drivers/gpu/drm/drm_edid.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -3216,6 +3216,7 @@ static u8 drm_find_displayid_extension(const struct edid edid,
		int length, int idx)
		{
		u8 *displayid = drm_find_edid_extension(edid, DISPLAYID_EXT);
		struct displayid_hdr *base;
		int ret;

		if (!displayid)
		@@ -3228,6 +3229,9 @@ static u8 drm_find_displayid_extension(const struct edid edid,
		if (ret)
		return NULL;

		base = (struct displayid_hdr )&displayid[idx];
		length = idx + sizeof(*base) + base->bytes;

		return displayid;
		}

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