diff options
| author | Douglas Anderson <dianders@chromium.org> | 2021-10-05 19:29:08 -0700 |
|---|---|---|
| committer | Dave Airlie <airlied@redhat.com> | 2021-10-15 15:03:57 +1000 |
| commit | 97794170b696856483f74b47bfb6049780d2d3a0 (patch) | |
| tree | 0b007762cc0df2094b3c4d2c1e250ea3e89e715d | |
| parent | 6011106d129d8249baad3426fae13f147d9ffa65 (diff) | |
drm/edid: In connector_bad_edid() cap num_of_ext by num_blocks read
In commit e11f5bd8228f ("drm: Add support for DP 1.4 Compliance edid
corruption test") the function connector_bad_edid() started assuming
that the memory for the EDID passed to it was big enough to hold
`edid[0x7e] + 1` blocks of data (1 extra for the base block). It
completely ignored the fact that the function was passed `num_blocks`
which indicated how much memory had been allocated for the EDID.
Let's fix this by adding a bounds check.
This is important for handling the case where there's an error in the
first block of the EDID. In that case we will call
connector_bad_edid() without having re-allocated memory based on
`edid[0x7e]`.
Fixes: e11f5bd8228f ("drm: Add support for DP 1.4 Compliance edid corruption test")
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211005192905.v2.1.Ib059f9c23c2611cb5a9d760e7d0a700c1295928d@changeid
Signed-off-by: Dave Airlie <airlied@redhat.com>
| -rw-r--r-- | drivers/gpu/drm/drm_edid.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index 6325877c5fd6..ea9a79bc9583 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -1834,11 +1834,20 @@ static void connector_bad_edid(struct drm_connector *connector, u8 *edid, int num_blocks) { int i; - u8 num_of_ext = edid[0x7e]; + u8 last_block; + + /* + * 0x7e in the EDID is the number of extension blocks. The EDID + * is 1 (base block) + num_ext_blocks big. That means we can think + * of 0x7e in the EDID of the _index_ of the last block in the + * combined chunk of memory. + */ + last_block = edid[0x7e]; /* Calculate real checksum for the last edid extension block data */ - connector->real_edid_checksum = - drm_edid_block_checksum(edid + num_of_ext * EDID_LENGTH); + if (last_block < num_blocks) + connector->real_edid_checksum = + drm_edid_block_checksum(edid + last_block * EDID_LENGTH); if (connector->bad_edid_counter++ && !drm_debug_enabled(DRM_UT_KMS)) return; |