diff options
| author | Jani Nikula <jani.nikula@intel.com> | 2026-06-25 13:44:07 +0300 |
|---|---|---|
| committer | Joonas Lahtinen <joonas.lahtinen@linux.intel.com> | 2026-06-30 09:35:52 +0300 |
| commit | db9e64c983dcb07ff256bd455f258c44aa530ff8 (patch) | |
| tree | f86235c6f960da7fcb84cfcda1a8207dfad9a021 | |
| parent | bbb15a6b042d02e5508a02b4847e02d2579ee7bc (diff) | |
drm/i915/hdcp: require monotonically increasing seq_num_v
The HDCP 2.2 specification requires the seq_num_v to be monotonically
increasing, and repeated seq_num_v needs to be treated as an integrity
failure. Make it so.
For the first message, seq_num_v must be zero, and is already
checked. We can only check for less-than-or-equal for the subsequent
messages, where hdcp2_encrypted is true.
Discovered using AI-assisted static analysis confirmed by Intel Product
Security.
Reported-by: Martin Hodo <martin.hodo@intel.com>
Fixes: d849178e2c9e ("drm/i915: Implement HDCP2.2 repeater authentication")
Cc: stable@vger.kernel.org # v5.2+
Cc: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patch.msgid.link/20260625104407.1025614-1-jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
(cherry picked from commit 58a224375c81179b52558c53d8857b93196d2687)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
| -rw-r--r-- | drivers/gpu/drm/i915/display/intel_hdcp.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c index 521786a75c42..0a076d2ed70a 100644 --- a/drivers/gpu/drm/i915/display/intel_hdcp.c +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c @@ -1801,9 +1801,10 @@ int hdcp2_authenticate_repeater_topology(struct intel_connector *connector) return -EINVAL; } - if (seq_num_v < hdcp->seq_num_v) { - /* Roll over of the seq_num_v from repeater. Reauthenticate. */ - drm_dbg_kms(display->drm, "Seq_num_v roll over.\n"); + if (hdcp->hdcp2_encrypted && seq_num_v <= hdcp->seq_num_v) { + /* Reauthenticate on Seq_num_v repeat or rollover */ + drm_dbg_kms(display->drm, "Seq_num_v %s\n", + seq_num_v == hdcp->seq_num_v ? "repeat" : "rollover"); return -EINVAL; } |