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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:d849178e2c("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 commit58a224375c) Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>